universiti teknologi mara design of plasma · pdf file1 universiti teknologi mara design of...
TRANSCRIPT
1
UNIVERSITI TEKNOLOGI MARA
DESIGN OF PLASMA ANTENNA FOR
RECONFIGURABLE BEAM STEERING
TECHNIQUE
HAJAR BINTI JA’AFAR
PhD
January 2016
i
UNIVERSITI TEKNOLOGI MARA
DESIGN OF PLASMA ANTENNA FOR
RECONFIGURABLE BEAM STEERING
TECHNIQUE
HAJAR BINTI JA’AFAR
Thesis submitted in fulfillment
of the requirement for the degree of
Doctor of Philosophy
Faculty of Electrical Engineering
January 2016
ii
CONFIRMATION BY PANEL OF EXAMINERS
I certify that a Panel of Examiners has met on 22 October 2015 to conduct the final
examination of Hajar Binti Ja’afar on her Doctor of Philosophy thesis entitled "Design
of “Plasma Antenna For Reconfigurable Beam Steering Technique” in accordance
with Universiti Teknologi MARA Act 1976 (Akta 173). The Panel of Examiners
recommends that the student be awarded the relevant degree. The panel of Examiners
was as follows:
Datin Shah Rizam Mohd Shah Baki,PhD
Professor,Ir
Faculty of Electrical Engineering
Universiti Teknologi MARA
(Chairman)
Nur Emileen Abd Rashid, PhD
Senior Lecturer
Faculty of Electrical Engineering
Universiti Teknologi MARA
(Internal Examiner)
Mohammad Tariqul Islam, PhD
Professor
Faculty of Engineering & Built Environment,
Universiti Kebangsaan Malaysia,
(External Examiner)
SAULEAU, Ronan, PhD
Professor
Antennes et Dispositifs Hyperfréquences
University of Rennes 1 (UR1)
(External Examiner)
SITI HALIJJAH SHARIFF, PhD
Associate Professor
Dean
Institute of Graduate Studies
Universiti Teknologi MARA
Date : 11th
January 2016
iii
AUTHOR’S DECLARATION
I declare that the work in this thesis was carried out in accordance with the regulations
of Universiti Teknologi MARA. It is original and is the results of my own work,
unless otherwise indicated or acknowledge as referenced work. This thesis has not
been submitted to any other academic institution or non-academic institution for any
degree or qualification.
I, hereby, acknowledge that I have been supplied with the Academic Rules and
Regulations for Post Graduate, Universiti Teknologi MARA, regulating the conduct of
my study and research.
Name of Student : Hajar Binti Ja’afar
Student I.D No : 2011595953
Programme : Doctor of Philosophy (Electrical Engineering)
Faculty : Faculty of Electrical Engineering
Thesis Title : Design of Plasma Antenna for Reconfigurable Beam
Steering Technique
Signature of Student : ……………………………
Date : January 2016
iv
ABSTRACT
The industrial potential of plasma technology is well known and excellent
demonstrated in several processes of microwave technology, which incorporate some
use of an ionized medium. In vast majority of approaches, the plasma, or ionized
volume, simply replaced a solid conductor. Highly ionized plasma is essentially a
good conductor, and therefore plasma filaments can serve as transmission line
elements for guiding waves, or antenna surfaces for radiation. Plasma antenna is a
kind of antenna that radiate electromagnetic wave (EM) energy based on ionized gas
instead of metallic conductor in antenna design. In this research work, the
development using plasma medium as a conductor element instead of metal medium is
investigated. Three new design antenna by using plasma concepts were proposed;
namely cylindrical monopole plasma antenna using electrode-less discharge tube,
monopole plasma antenna using fluorescent tube and reconfigurable plasma antenna
array. The research described in this project introduces the analysis of cylindrical
monopole plasma antenna. Three types of gases with three different pressure which
are Argon gas, Neon gas and Hg-Ar gas (mixture of Argon gas and mercury vapor)
with pressure at 0.5 Torr, 5 Torr and 15 Torr respectively is used in this research to
observe the interaction between plasma medium and radio frequency (RF) signal. The
containers that use to fill the gas are namely electrode-less discharge tube. The
technique that used in this experiment to generate plasma is using Dielectric Barrier
Discharge (DBD). The monopole plasma antenna using fluorescent tube is designed at
frequency 2.4 GHz which is aim in wireless application. The commercially
fluorescent lamp is used as a plasma antenna. Coupling technique was used in this
design. In the reconfigurable plasma antenna array, the behavior of the reconfigurable
antenna array system using plasma medium has been investigated and discuss with
respect to the beam shaping characteristics. The reconfigurable plasma antenna array
is capable of scanning the radiation pattern over 360°. These results confirm that the
main beam directions can be directed in the following directions depending on the
states of switches which are 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°,
300° and 330°. The simulated and measured results are presented and compared, to
demonstrate the performance of the proposed antennas.
v
ACKNOWLEDGEMENT
In the name of Allah, the Most Gracious The Most Merciful.
I am grateful for guidance and continuous supports from my supervisor, Assoc Prof.
Dr. Mohd Tarmizi bin Ali. His inspiring advices and commitment during the period
of this work are invaluable. My particular thanks go to my second supervisor, Dr.
Ahmad Nazri bin Dagang, for his advices in numerous discussions especially on the
plasma parts.
My appreciations go to Mr Mohammad Khalim Kamsan, who helped me in the
technical parts including fabrications and measurements and lab technicians for their
guidance and assistance. I also appreciate to all my colleagues of Antenna Research
Group (ARG), Microwave Technology Center (MTC), Faculty of Electrical
Engineering, Universiti Teknologi MARA (UiTM), who have provided assistance and
for the memorable time spent together throughout the 3 years. The sweet memories
that we had shared are safely embedded in my heart and it will not be erased over
time.
I would like to acknowledge the Ministry of Higher Education, Malaysia and
University Teknologi MARA,Malaysia (UiTM) for the financial support throughout
my study.
I am also truly grateful to my parents (Mr. Ja’afar bin Mohd Tap and Mdm.
Satariah binti Hasan), parents in-law (Mr. Md Said bin Ayob and Mdm. Zaleha
binti Mohd) for their belief in me and their prayers during my doctoral journey. To
my siblings, the support and the prayers will never be paid by me.
I owed thanks to a very special person, my beloved and understanding husband Mr.
Mohd Amir Nurasyid bin Md Said for his unconditional support through the thick
and thin and also to my beloved and pretty daughter, Zara Sophea binti Mohd Amir
Nurasyid, I would like to express my thanks for being such a good girl always
cheering me up. Words would never say how grateful I am to both of you. I consider
myself the luckiest in the world to have such a lovely and caring family, standing
beside me with their love and unconditional support.
vi
TABLE OF CONTENTS
Page
CONFIRMATION BY PANEL OF EXAMINERS ii
AUTHOR’S DECLARATION iii
ABSTRACT iv
ACKNOWLEGMENT v
TABLE OF CONTENTS vi
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF SYMBOLS xix
LIST OF ABBREVIATIONS xx
CHAPTER ONE: INTRODUCTION
1
1.1 Research Background 1
1.2 Problem Statement 4
1.3 Objectives 6
1.4 Scope of Work 6
1.5 Thesis Organization 7
CHAPTER TWO : BACKGROUND AND LITERATURE REVIEW
9
2.1 Introduction 9
2.2 Fundamental of Plasma 10
2.3 Ionization Process In Plasma Medium 11
2.4 Method of Generating Plasma 13
2.4.1 Electrode Discharge Tube 13
2.4.1.1 Plasma Generated by Using DC and AC 14
2.4.2 Electrode-less Discharge Tube 19
2.4.2.1 Capacitively Discharge Plasma(CDP) 19
2.4.2.2 Inductively Coupled Plasma (ICP) 22
2.4.2.3 Microwave Plasma 23
2.4.2.4 Radio Frequency (RF) Plasma 25
vii
2.4.2.5 Laser 27
2.5 Plasma Antenna Technology 29
2.5.1 Coupling Technique 29
2.5.2 Shape of Plasma Antenna 35
2.5.3 Reconfigurable Plasma Antenna 38
2.6 Summary 44
CHAPTER THREE: RESEARCH METHODOLOGY
46
3.1 Introduction 46
3.2 Research Methodology 47
3.3 Fundamentals Parameters of Plasma Physics for Plasma Antenna 52
3.3.1 Plasma Frequency 52
3.3.2 Plasma Collision Frequency 54
3.3.3 Conductivity of the Plasma Medium 56
3.3.4 Complex Dielectric Permittivity of the Plasma Medium 59
3.4 Estimation of Plasma and Collision Frequency 60
3.5 Drude Dispersion Model for Designing Plasma 64
3.6 Fabrication and Measurement Setup 65
3.6.1 Fabrication Process 65
3.6.1.1 Cylindrical Monopole Plasma Antenna Using Electrode-Less
Discharge Tube
65
3.6.1.2 Monopole Plasma Antenna using Fluorescent Tube 68
3.6.1.3 Reconfigurable Plasma Antenna Array 70
3.6.2 Measurement Setup 73
3.6.2.1 Return Loss Measurement 73
3.6.2.2 Radiation Pattern Measurement 74
3.6.2.3 Radiation Signal Measurement 75
3.6.2.4 Measurement of Radiation Signal from Monopole Plasma
Antenna as a Transmitter
77
3.6.2.5 Measurement of Radiation Signal from Monopole Plasma
Antenna as a Receiver
77
3.6.2.6 Measurement of Signal Strength Monopole Plasma Antenna 78
viii
3.7 Summary 78
CHAPTER FOUR: A CHARACTERISTIC OF CYLINDRICAL
MONOPOLE PLASMA ANTENNA
80
4.1 Introduction 80
4.2 Electrode-Less Discharge For Dielectric Barrier Discharge 81
4.3 Design of Cylindrical Monopole Plasma Antenna 82
4.3.1 Design Procedure 82
4.3.2 Structure of Cylindrical Monopole Plasma Antenna 83
4.4 Analysis of Cylindrical Monopole Plasma Antenna 84
4.4.1Effect of Plasma Frequency on Complex Permittivity 84
4.4.2 Effect of Different Pressure 87
4.4.2.1 Argon Gas 87
4.4.2.2 Neon Gas 89
4.4.2.3 Hg-Ar Gas 92
4.4.3 Comparison of Different Gas Performance 94
4.5 Results and Discussion 100
4.6 Summary 104
CHAPTER FIVE: DEVELOPMENT MONOPOLE PLASMA
ANTENNA USING FLUORESCENT TUBE FOR WIRELESS
TRANSMISSION
106
5.1 Introduction 106
5.2 Mercury –Argon (Hg-Ar) Fluorescent Lamp 107
5.3 Parameter Study On A Monopole Plasma Antenna Using Fluorescent Tube 108
5.3.1 Effects of the Length of Monopole Plasma Antenna 111
5.3.2 Effects of Diameter Plasma Antenna 112
5.3.3 Effects of Parameter for Coupling Sleeve 112
5.4 Analysis Between Monopole Plasma Antenna and Metal Antenna 115
5.5 Simulation and Measurement Results 117
5.6 Wireless Signal Transmission Experiment 119
5.6.1 Experiment Radiation Signal 119
5.6.2 Monopole Plasma Antenna as a Transmitter 121
ix
5.6.3 Monopole Plasma Antenna as a Receiver 122
5.6.4 Signal Strength for Monopole Plasma Antenna 123
5.7 Summary 124
CHAPTER SIX: DEVELOPMENT OF RECONFIGURABLE PLASMA
ANTENNA ARRAY
126
6.1 Introduction 126
6.2 Reconfigurable Plasma Antenna Array 126
6.2.1 Reconfigurable Plasma Antenna Array Structure 127
6.3 Analysis of Reconfigurable Plasma Antenna Array 129
6.3.1 Effect of Distance Between Monopole Antenna to Fluorescent
Tube,DBB
129
6.3.2 Effect of Thickness of Ground,t 131
6.3.3 Effect of Length of Monopole Antenna,LM 132
6.3.4 Effect of Numbers of Fluorescent Tubes and Adjacent Angle,θ 133
6.3.5 Effect of Fluorescent Tubes on Radiation Pattern 135
6.4 Switching Pattern of Reconfigurable Plasma Antenna Array for Beam
Scanning
136
6.5 Simulation and Measurement Results of Reconfigurable Plasma Antenna
Array
145
6.6 Summary 154
CHAPTER SEVEN : CONCLUSION, FUTURE WORKS AND
RESEARCH CONTRIBUTION
156
7.1 Conclusion 156
7.2 Future Works 157
7.2.1 Different Types of Gases 158
7.2.2 Operating Frequency 158
7.2.3 Different Shape of Plasma Antenna 158
7.3 Research Contribution 158
REFRENCES 160
APPENDICES 171
AUTHOR’S PROFILE 198
x
LIST OF TABLES
Tables Title Page
Table 2.1 Types of electrode less discharge lamps and their applications 19
Table 4.1 The parameters of a monopole plasma antenna 83
Table 4.2 The performance of cylindrical monopole plasma antenna using
argon gas
89
Table 4.3 The performance of cylindrical monopole plasma antenna using
neon gas
92
Table 4.4 The performance of monopole plasma antenna using Hg-Ar gas 94
Table 4.5 The performance of monopole plasma antenna for different gases
at pressure 0.5 Torr
99
Table 4.6 The performance of monopole plasma antenna for different gases
at pressure 5 Torr
99
Table 4.7 The performance of monopole plasma antenna for different gases
at pressure 15 Torr
100
Table 5.1 Optimized parameters for monopole plasma antenna 110
Table 5.2 Summary results signal strength for three conditions 120
Table 6.1 Optimized reconfigurable plasma antenna array specifications 129
Table 6.2 The performances analysis of the number of element and the angle
between two adjacent elements
134
Table 6.3 Summary of switching pattern of reconfigurable plasma antenna
array for beam scanning
141
Table 6.4 Switching setting for reconfigurable plasma antenna array (Blue
color represent activated elements ( switched ON), while white
color represent deactivated elements (switched OFF))
141
Table 6.5 Simulated Radiation Characteristics of reconfigurable plasma
antenna array
151
xi
LIST OF FIGURES
Figures Title Page
Figure 2.1 Change in state of matter 11
Figure 2.2 Ionization process 11
Figure 2.3 Ionized plasma at loop antenna 12
Figure 2.4 Range of electron temperature and electron density for typical
plasma found in nature and in technological applications
13
Figure 2.5 A schematic diagram for electrode discharge tube 14
Figure 2.6 (a) The schematic diagram of plasma antenna (b) the real
prototype for plasma antenna
15
Figure 2.7 (a) The gain versus frequency curve of metal (b) The gain
versus frequency Neon plasma antenna
15
Figure 2.8 The radiation pattern of metal antenna at 8.2 GHz (b) The
radiation pattern of Neon plasma antenna
16
Figure 2.9 The plasma antenna construction 17
Figure 2.10 Measurement of return loss during switch off mode marked as
curve A and switch on mode marked as curve B and C
17
Figure 2.11 Monopole plasma antenna radiation pattern at 590 MHz. Array
1(red line) is the co-polarization and Array 2(blue line) is the
cross polarization
18
Figure 2.12 220V AC-driven plasma antenna 18
Figure 2.13 The common diagram of BDB 20
Figure 2.14 Schematic diagram of the DBD plasma setup. A pair of
circular aluminum plate electrodes was covered with quartz
glasses
21
Figure 2.15 Typical capacitively coupled RF plasma reactor 21
Figure 2.16 The Schematic diagram of experimental apparatus of CCP. 22
Figure 2.17 Plasma formation by using ICP method 22
Figure 2.18 Schematic diagram to generate plasma 23
xii
Figure 2.19 Plasma column generate using microwave plasma 24
Figure 2.20 Longitudinal section of the surfaguide. The vertical tube
contains plasma to be ignited
24
Figure 2.21 Experiment set up for plasma antenna 25
Figure 2.22 The monopole plasma antenna 26
Figure 2.23 Schematic of plasma antenna 26
Figure 2.24 The radiation pattern for copper metal antenna (b) The
radiation pattern for plasma antenna
27
Figure 2.25 Schematic diagram of the RF propagation experiment 28
Figure 2.26 Schematic diagram for a proposed Beverage Antenna 28
Figure 2.27 Plasma antenna using coupling technique 29
Figure 2.28 Plasma antenna (a) Using a standard U-shape fluorescent lamp
(b) coupling sleeve
30
Figure 2.29 Coupling structures (a) Inductive coupling (b) Double
inductive coupling (c) Capacitive coupling
31
Figure 2.30 Block diagram of the plasma antenna circuit and
measurements systems
31
Figure 2.31 Transmission characteristics (S21) for two type of coupling
structures with different configurations
32
Figure 2.32 Coupling sleeve in an excitation box 33
Figure 2.33 Coupling between the two ports with (black) and without
(gray) the conducting medium
33
Figure 2.34 Reflection coefficient of the signal port with (black) and
without (gray) the plasma
33
Figure 2.35 Three different kinds of couplers (a) Solenoid Coupling (b)
Cubic coupling (c) Cylindrical coupling
34
Figure 2.36 The ideal model of plasma helix antenna 35
Figure 2.37 Comparison results for radiation pattern between metal
antenna and plasma helix antenna (a) Horizontal plane (b)
vertical plane
36
Figure 2.38 Return loss, S11 of plasma helix antenna 36
xiii
Figure 2.39 A model of a plasma whip antenna located on dielectric
substrate with relative permittivity of 2.35 and the thickness, h
is 2 mm
36
Figure 2.40 Comparison results of return loss between plasma whip
antenna and metal antenna
37
Figure 2.41 A plasma triangular monopole antenna 38
Figure 2.42 Plasma antenna (a) Single plasma antenna (b) Array plasma
antenna
39
Figure 2.43 Comparison between normalized elevation radiation patterns
of single and array plasma antenna
39
Figure 2.44 The schematic diagram of plasma antenna 40
Figure 2.45 The helical plasma antenna 40
Figure 2.46 The diagram of experimental setup 41
Figure 2.47 (a) The plasma column when driven power is 15 W (b) The
plasma column when driven power is 39 W
41
Figure 2.48 Plasma reflector antenna installed in anechoic chamber 42
Figure 2.49 Radiation Patterns of Plasma Reflector Antenna and Metal
Reflector Antenna
42
Figure 2.50 Geometry of reconfigurable plasma corner reflector antenna 43
Figure 2.51 The 24 plasma elements for reconfigurable plasma corner
reflector antenna with a monopole antenna in the center of the
ground plane.
43
Figure 2.52 Normalized H-plane radiation patterns, (a) Simulation. (b)
Measurement
44
Figure 3.1 Flow chart of the research (a) Cylindrical monopole plasma
antenna (b) Monopole plasma antenna using fluorescent lamp
and (c) Reconfigurable plasma antenna array
49
Figure 3.2 Flow diagram of GLOMAC to calculate electron density for
argon and neon gases
61
Figure 3.3 Flow diagram of GLOMAC to calculate electron density for
mixture of argon and mercury vapor
62
Figure 3.4 Defining a plasma in CST 64
Figure 3.5 Monopole plasma antenna using electrode-less discharge tube 67
xiv
(a) schematic diagram (b) construction of monopole plasma
antenna
Figure 3.6 Photograph of neon gas discharge tube at 15 Torr 67
Figure 3.7 Photograph of argon gas discharge tube at 15 Torr 68
Figure 3.8 Position of coupling sleeve 69
Figure 3.9 Monopole plasma antenna using fluorescent tube (a)
Schematic diagram (b) Construction monopole plasma antenna
69
Figure 3.10 Monopole plasma antenna integrated with 3G Wi-Fi router. 70
Figure 3.11 Monopole plasma antenna integrated with 3G Wi-Fi router
during switch ON
70
Figure 3.12 Geometry of reconfigurable plasma antenna array (a) Side
view (b) Top view
71
Figure 3.13 Prototype of reconfigurable plasma antenna array (a) 3D
AutoCAD drawing (b) Connection of 1 of fluorescent tube (c)
Prototype of reconfigurable plasma antenna array
72
Figure 3.14 Setup for return loss measurement 73
Figure 3.15 The radiation patterns measurement setup. The actual inside
view of the anechoic chamber room
74
Figure 3.16 The radiation patterns measurement setup. Equipment for
radiation patterns measurement
75
Figure 3.17 The layout of the measurement setup for radiation pattern
measurement
75
Figure 3.18 Coupling sleeve is wrapping with aluminum shielding box (a)
left view (b) right view (c) bottom view (d) top view
76
Figure 3.19 Coupling sleeve is wrapping with aluminum shielding box (a)
Front view during fluorescent tube switched OFF (b) Front
view during fluorescent tube switched ON
76
Figure 3.20 Experimental setup for plasma antenna that serves as a
transmitter
77
Figure 3.21 Experimental setup for plasma antenna that serves as a receiver 77
Figure 3.22 Testing the signal strength of monopole plasma antenna 78
Figure 4.1 A simple schematic diagram of a capacitive discharge 82
Figure 4.2 The schematic diagram of discharge tube 83
xv
Figure 4.3 Discharge tube used in this experiment 83
Figure 4.4 Relative Permittivity for argon gas, neon gas and Hg-Ar gas
for (a)0.5 Torr (b) 5 Torr and (c) 15 Torr
85
Figure 4.5 The effect on reflection coefficient, S11for different pressure
for Argon gas
87
Figure 4.6 The effect on VSWR for different pressure for Argon gas 88
Figure 4.7 Comparison of different pressure for Argon gas radiation
patterns in polar-plot
88
Figure 4.8 The effect of reflection coefficient, S11 for Neon gas at
different pressure
90
Figure 4.9 The effect of VSWR for different pressure for Neon gas 90
Figure 4.10 Comparison of different pressure for Neon gas radiation
patterns in polar-plot
91
Figure 4.11 The effect of reflection coefficient, S11for different pressure for
Hg-Ar gas
93
Figure 4.12 The effect of VSWR for different pressure for Hg-Ar gas 93
Figure 4.13 Comparison of different pressure for Hg-Ar gas radiation
patterns in polar-plot
94
Figure 4.14 The effect of reflection coefficient, S11 for different gas at (a)
0.5 Torr (b) 10 Torr and (c) 15 Torr
95
Figure 4.15 Comparison of simulated VSWR for different gases at (a) 0.5
Torr (b) 5 Torr and (c) 15 Torr
97
Figure 4.16 The effect of radiation pattern in polar plot for different gas at
(a) 0.5 Torr (b) 10 Torr and (c) 15 Torr
99
Figure 4.17 Simulated and measured reflection coefficient, S11 of cylindrical
monopole plasma antenna. (a) Argon gas at 0.5 Torr. (b) Neon gas
at 0.5 Torr. (c) Hg-Ar gas at 0.6 Torr.
101
Figure 4.18 Simulated and measured radiation patterns. (a) At frequency 4.6
GHz Argon gas in H-plane (left) and in E-plane (right). (b) At
frequency 4.6 GHz Neon gas in H-plane (left) and in E-plane (right).
(c) At frequency 4.5 GHz for Hg-Ar gas in H-plane (left) and in E-
plane (right).
103
Figure 5.1 Construction of the Fluorescent Lamp 108
xvi
Figure 5.2 The structure of a monopole plasma antenna 109
Figure 5.3 The effects on reflection coefficient, S11 due to change of
length monopole plasma antenna
111
Figure 5.4 The effects on reflection coefficient, S11 due to change of the
diameter of plasma antenna
112
Figure 5.5 Coupling sleeve structure 113
Figure 5.6 Effects on reflection coefficient of parameter for coupling
sleeve. (a) Numbers of turns (b) Width of aluminum tape (c)
Position of coupling sleeve (d) Diameter of coil (e) Distance
between SMA connector to coupling sleeve
113
Figure 5.7 Comparison of simulation results of reflection coefficient,S11
between metal antenna, condition during plasma OFF and ON
116
Figure 5.8 VSWR for plasma antenna on, off and metal antenna 116
Figure 5.9 Simulated radiation patterns of plasma monopole antenna
during ON,OFF and metal antenna in polar plots in the E-plane
(phi = 90°)
117
Figure 5.10 Simulated and measured reflection coefficient,S11 for
monopole plasma antenna
118
Figure 5.11 Simulated and measured radiation patterns of monopole plasma
antenna (ON) at 2.4 GHz in (a) H-Plane and (b) E-Plane.
119
Figure 5.12 Captured signal when plasma antenna serves as transmitter 121
Figure 5.13 Noise floor when the RF generator is turned off. 122
Figure 5.14 Captured signal when plasma antenna serves as receiver. 122
Figure 5.15 Noise floor when the plasma antenna was removed from the
receiver system.
123
Figure 5.16 Performance of Signal Strength when the fluorescent tube
antenna was connected to the AP Router
124
Figure 5.17 Performance of Signal Strength when fluorescent tube antenna
disconnected from AP Router
124
Figure 6.1 Geometry of the reconfigurable plasma antenna array (a) top
view (b) side view (c) overall structure
128
Figure 6.2 The effect of distance between monopole antenna to
fluorescent tube
130
xvii
Figure 6.3 Comparison of simulated gains at frequency 2.4 GHz in H-
Plane
130
Figure 6.4 Comparison of radiation patterns in polar-plot in H-plane 131
Figure 6.5 Effect on S11 when t is varied 132
Figure 6.6 Effect on reflection coefficient, S11 and resonant frequency
when LM is varied
132
Figure 6.7 Relationship between the number of fluorescent tubes and
adjacent angle. (a) 10 fluorescent tubes were used with only 6
elements activated (b) 12 fluorescent tubes were used with
only 7 elements activated (c) 20 fluorescent tubes were used
with only 15 elements activated.
133
Figure 6.8 Simulated radiation pattern in polar plot in (a) E-Plane and (b) H-
plane.
133
Figure 6.9 Simulation reflection coefficient,S11 134
Figure 6.10 Simulation and measurement results for radiation pattern in H-plane
(right) and E-plane (left). (a) Plasma off. (b) Monopole antenna
only.
135
Figure 6.11 Comparison between monopole and plasma off for simulation
results gain (dB) versus frequency (GHz)
136
Figure 6.12 Switching numbering for reconfigurable plasma antenna array 137
Figure 6.13 Simulated reflection coefficients, S11for switching pattern of
reconfigurable plasma antenna array
138
Figure 6.14 Measured reflection coefficients, S11 for switching pattern of
plasma antenna array
138
Figure 6.15 Simulated radiation pattern at 2.4 GHz for switching pattern of
reconfigurable plasma antenna array (a) in H-plane and (b) in E-
plane.
139
Figure 6.16 Measured radiation pattern at 2.4 GHz for switching pattern of
reconfigurable plasma antenna array (a) in H-plane and (b) in E-
plane.
139
Figure 6.17 Simulated result for different number of elements in H-plane
(ϕ =50 °) (a) Gain in dB (b) Directivity in dBi.
140
Figure 6.18 Remote control and receiver 143
xviii
Figure 6.19 Photograph of the overall structure of reconfigurable plasma
antenna array integrated with Arduino technology
144
Figure 6.20 Remote control with the main components 144
Figure 6.21 (a) Circuit at the remote control (b) Circuit at the receiver 145
Figure 6.22 Schematic drawing of reconfigurable plasma antenna array (a)
overall view (b) side view
146
Figure 6.23 Prototype of the reconfigurable plasma antenna arrays (a) De-
activated (Plasma off) of 12 fluorescent tubes. (b) 5/12 plasma
in ON condition
146
Figure 6.24 Simulated of reflection coefficient,S11 146
Figure 6.25 Simulated results of radiation pattern for reconfigurable
plasma antenna array at different switch configuration modes.
147
Figure 6.26 Combination of simulated scanning radiation patterns in the H-
plane for reconfigurable plasma antenna array
150
Figure 6.27 Simulated peak gains (abs) of reconfigurable plasma antenna
array with different main lobe directions at frequency 2.4 GHz
150
Figure 6.28 Reflection coefficient, S11 (a) Measurement (b) Simulation 151
Figure 6.29 Simulated and measured radiation pattern in H-plane at
frequency 2.4 GHz
152
xix
LIST OF SYMBOLS
Symbols
c Speed of light
Permittivity
Permittivity of free space
Complex permittivity
Relative dielectric constant at infinity frequency
λ Wavelength
J Current density
Electron mass
Electron density
θ Adjacent angle
ρ Charge density
Electron charge
Plasma frequency
Electromagnetic wave frequency
σ Plasma conductivity
S11 Antenna reflection coefficient/S-parameter
Collision frequency
Cathode fall voltage
xx
LIST OF ABBREVIATIONS
Abbreviations
AC Alternating current
AP Access point
Ar2 Argon gas
AUT Antenna under test
CCP Capacitively coupled plasma
CDP Capacitively discharge plasma
CST Computer Simulation Technology
DBD Dielectric barrier discharge
DC Direct current
EMI Electromagnetic interference
eV Electron volts
FM Frequency modulation
HF High frequency
HFSS High Frequency Structural Simulator
Hg-Ar Mixture of mercury vapor and argon gas
HPBW Half power beamwidth
H20 Water
ICP Inductively coupled plasma
MP Microwave plasma
Ne2 Neon gas
PC Positive column
RF Radio frequency
SMA SubMiniature version A
Tx Transmitter
UHF Ultra High Frequency
UV Ultra Violet
VHF Very High Frequency
VNA Vector Network Analyzer
VSWR Voltage Standing Wave Ratio
xxi
1
CHAPTER ONE
INTRODUCTION
1.1 RESEARCH BACKGROUND
In recent years, the current electronic communications industry has required high
performance and efficient systems to meet the demands of the present continuously
evolving applications. Nevertheless, physical limitations of microwave devices and
circuits have stalled further improvements of the current technology. Besides, the
rapid advances in technology have also significantly resulted in high demand for
multi-function devices, including the antennas. Therefore, to cope with this demand,
multi-function antennas can be considered as one of the key advances in future
wireless communications technology. However, the development of these antennas
has posed significant challenges to antenna designers particularly. In the midst of this
scenario, the usage of plasma as a conductive element in microwave devices has
drawn growing interest due to their peculiar and innovative properties with respect to
the traditional metallic circuits. At present, the industrial potential of plasma
technology is well-known and has been excellently demonstrated in several processes
of microwave technology, which incorporates the use of an ionized medium.
The term plasma is often referred to as the fourth state of matter. As the
temperature increases, molecules become more energetic and transform in the
sequence of solid to liquid to gas and plasma. The existence of plasma was first
discovered by Sir William Crookes in 1879. In 1919, the concept of plasma antenna
was patented and the patent was awarded to J. Hettinger with the name of "Aerial
conductor for wireless signaling and other purposes" [1].
Besides, applications of plasma find wider use in our technology every day. From
huge and sophisticated projects of fusion to material processing to simple lighting
equipment, the plasma research is one of the most generously funded research topics.
On many of the plasma applications, the plasma is generated, heated or manipulated
by RF radiation [2]. The plasma is a state of matter in which charged particles such as
electrons and atom nuclei have sufficiently high energy to move freely, rather than be
2
bound in atoms as in ordinary matter. Some examples of plasma are the fluorescent
lighting tubes, lightning, and ionosphere.
Furthermore, due to the unique characteristic of plasma which can be a conductor,
it can be combined with antenna concepts and hence, make plasma antennas. Plasma
antenna is a type of radio antenna that represents the use of ionized gas as a
conducting medium instead of metal conductors to either transmit or receiver the radio
frequency signal [3]. Recently, there has been a resurgence of interest in plasma
antenna technology. The plasma is rapidly created and destroyed with applying proper
radio frequency (RF) power pulses to the discharge tube so that the antenna is
switched on and off. When the antenna is off, the plasma is non-conducting, and
therefore the tube is practically transparent and behaves like a dielectric material,
whereas when the plasma is on, it exhibits high conductivity, providing a conducting
medium for the applied RF signal [4-5]. Thus the advantage in using plasma antennas
instead of conventional antenna is that they allow an electrical rather than physical
control. In particular, for military applications, when a plasma antenna is off ( not
energized) it is difficult to detect with a hostile radar if its tube is properly designed
compared to the conventional antenna due to material effect. This is because when a
plasma element is not energized, it is transparent to the transmission above the plasma
frequency, which falls in the microwave region [6]. Besides, by using plasma antenna
in military application, it can reduce the usage of multiple antennas as well. The
ability plasma antenna to be dynamically tuned and reconfigured for frequency,
direction, bandwidth, gain and beamwidth in a single antenna could help the system in
military to suite its requirement variation and to stay dependable [7].
On top of that, plasma element can also be applied as an antenna element for
conventional communication systems. Since plasma is highly reconfigurable, the
unused elements do not cause any unwanted effect to the whole systems. Besides, the
implementation of plasma antenna enables the communication system to adjust its
radio performances in order to suite and meet the changing of system requirement due
to the system itself or due to environmental requirement. In addition, the
communication systems at present have become more complex especially to cope with
the increasing number of users. Therefore with the ability of plasma, the
communication systems are capable to remain reliable over time.
3
The research contributions in this thesis describe the concept of plasma antenna
and beam switching using plasma element for communication application. There are
three types antenna structures were designed in this research work: first design is
cylindrical monopole plasma antenna using discharge tube, second design is
monopole plasma antenna using fluorescent tube and third design is the reconfigurable
plasma antenna array using fluorescent tube. The coupling technique was used in
designing the cylindrical monopole plasma antenna and the monopole plasma antenna
using fluorescent tube. In the cylindrical monopole plasma antenna, the interaction
between the plasma element and the electromagnetic wave was investigated .The
effects of plasma parameters, such as the different gases and the varying pressures to
the performances of the antenna, were investigate and are presented in chapter four. In
this model, the dielectric barrier charge was used to generate the plasma. Besides,
three different gases were analyzed which were argon gas, neon gas and Hg-Ar gas
with pressures 0.5 Torr, 5 Torr and 15 Torr respectively.
Meanwhile, the monopole plasma antenna using fluorescent tube and the
reconfigurable plasma antenna array using fluorescent tube were designed based on
commercial fluorescent lamp in the market. The monopole plasma antenna using
fluorescent tube and reconfigurable plasma antenna array using fluorescent tube were
designed at a target frequency of 2.4 GHz which was suitable for wireless application.
In monopole plasma antenna using fluorescent tube a fluorescent tube with a length of
589.8 mm and diameter 28 mm was used as a plasma antenna.
The result from the monopole plasma antenna using fluorescent tube showed that
fluorescent tube could be applied as a plasma antenna, and therefore, it proved that the
commercial fluorescent lamp possessed the potential to be used as a good conductor
element and also a low cost plasma antenna. Thus the next design still applied the
commercial fluorescent tube in this research. In reconfigurable plasma antenna array
using fluorescent tube, the concepts of reconfigurable and beam steering were
implement to design this antenna. By using the special properties of plasma, which
can be rapidly activated (switch ON) and de-activated (switch OFF) in few seconds,
the concept of reconfigurable radiation pattern was applied in this research. Besides,
with the implementation of reconfigurable plasma antenna array on a single ground
plane, the radiation pattern was enabled to reconfigure over 12 directions to be
4
realized just at fingertips. Hence, the relationship between the plasma element and the
radiation characteristic were investigated in this work.
Apart from that, the reconfigurable plasma antenna array had been a
reconfigurable antenna with a combination of monopole antenna and fluorescent tube
function as a plasma medium to produce beam steering control. In contrast to
conventional antennas that produce fixed directional radiation patterns, the
reconfigurable plasma antenna array structure is capable of scanning the beam pattern
over 360° .Simulated and measured results of tests on the three antennas are presented
and were compared to demonstrate the performance of the proposed antennas. These
results confirmed that the main beam directions could be pointed to the desired
direction by controlling the switches. Moreover, the direction of beam pattern could
rapidly change within split seconds with a fast switching scheme. In fact, the fastest
time taken to change the beam pattern direction depended only on the time taken by
the plasma to decay.
In addition, the entire switch configuration modes in all antennas design were
controlled by an Arduino microcontroller. Arduino can control the switching of the
plasma antenna whereby the users can control the ON and OFF of the fluorescent
lamp with remote control. Hence, the development of Arduino microcontroller was
programmed using the Arduino technology software.
In the Antenna Research Group (ARG), Universiti Teknologi MARA (UiTM)
Malaysia, this research had been one of the earliest works that dealt with plasma
antenna. Therefore, at this moment, this study is indeed very important since it would
become a starting point in the ARG so that other works will benefit from the output of
this work.
1.2 PROBLEM STATEMENT
The industrial potential of plasma technology is well known and has been
excellently demonstrated in several processes of microwave technology, which
incorporates some uses of an ionized medium. Nevertheless, despite of the numerous
advantages, the construction of a plasma based radiating element requires trial-and-
error experimental works due to lack of in-depth study on the fundamental mechanism
of plasma radiation itself. Thus, rigorous investigation on the physical interaction
mechanism between electromagnetic field and plasma had been necessary. The best
5
available option was to use computer (numerical) models of plasma antennas.
Therefore, there had been a need for computer (numerical) modeling to analysis the
characteristics of antennas, as well as to verify the parameters for future studies.
Besides, progress in the technology of wireless communication systems has
created a strong need for the development of new antenna structures. In wireless
communication systems, a conventional antenna is capable of producing only a fixed
directional radiation pattern [8]. This is not the case when using reconfigurable
antennas which can change the direction of the main lobe of a radiation pattern for
modern wireless communications. Moreover, reconfigurable antennas make it possible
for use of a single antenna for multiple applications. However, physical limitations of
the conventional antennas limit the dynamic range of beam steering due to inter-
element coupling effects and co-site interference [8–10].
On top of that, the antenna technology has been widely use in military
application. In fact, several papers have looked into antenna technology in military
application using conventional antenna [12–15]. However, the radar could detect the
conventional antenna due to the material antenna. Hence, it is very important to design
an antenna with good safety factor to avoid usage of antenna in military application
being discovered by the enemy.
Nowadays, the demand for modern and smart application in wireless
technology is rather high. The proper installment of a complete set of Wi-Fi systems
in the house or any indoor applications by using conventional metal antenna has
specific space constraint as the antenna is required to be placed at particular areas to
allow efficient coverage and signal. The unsuitable placing area makes the installment
parts of conventional metal antenna highly visible to others. However, this can be
eliminated by using plasma antenna technology. Plasma antenna is one of the
camouflage technologies that have streamline appearance in the space of an area. In
plasma antenna, by using commercial fluorescent lamp as a plasma medium, the
antenna possesses dual function at one time. Besides operating as a lighting source,
the plasma antenna using fluorescent lamp can serve as a Wi-Fi system, whereby the
lamp functions as an antenna at the same time.
6
1.3 OBJECTIVE OF THE RESEARCH
This research has beneficial implications for communication systems
environments. The development of antennas by using plasma medium instead of metal
element is definitely a good improvement in the antenna technology. This research
involved antenna design simulations, fabrications, and measurements in order to
develop the best possible types of antennas. Hence, the research was embarked based
on the following objectives:
1. To analyze and investigate the relationship between plasma behaviors with RF
characteristic.
2. To design and conduct experiment interaction between plasma element and RF
microwave with three types of gases which is argon gas, neon gas and Hg-Ar
gas (a mixture of mercury vapor and argon gas), as well as with pressures 0.5
Torr, 5 Torr and 15 Torr.
3. To design and develop plasma antenna as a radiating element by using
commercial fluorescent lamp for Wi-Fi application.
4. To design and develop a reconfigurable antenna by using plasma element with
capabilities of beam scanning and beam shaping.
5. To design and construct a microcontroller circuit with Arduino system, as well
as to implement it to a reconfigurable antenna. The reconfigurable antenna by
using plasma as its medium structure should be capable of scanning the beam
pattern over 360°.
1.4 SCOPE OF WORK
The main emphasis of this research was to design and to develop plasma antennas
based on plasma medium. In order to achieve that, the research had been divided into
two; software and hardware parts. The software part included the antenna design
process, its simulations, and also the switching circuit network design. Meanwhile, the
hardware part included the fabrication of the proposed antenna.
7
In order to start, a comprehensive review was required to obtain knowledge on
antenna design. The proposed antennas were designed and simulated using Computer
Simulation Technology (CST) Microwave Studio. Besides, to calculate the plasma
parameter such as plasma frequency and plasma density, GLOMAC simulation was
employed. GLOMAC is a computer code for describing low pressure gas such as
electron density and electron temperature.
In the other hand, switching circuit network was designed using Arduino.
Arduino is a single-board microcontroller, intended to make building interactive
objects or environments more accessible. The design parameters of both designs were
optimized to achieve, optimal results.
After satisfied results from the simulation were obtained, the prototype antennas
were fabricated and tested. The measurement of antenna reflection coefficient and
radiation pattern was carried out using Vector Network Analyzer (VNA) and spectrum
analyzer at anechoic chamber. Finally, the comparisons were made between
simulation and measurement results then analyzed and documented.
1.5 THESIS ORGANIZATION
The above serves as a general introduction to the background of this study and its
significances. The problem statements and research questions are also included. In
addition, the objectives of this study and the scope of work are also noted.
Chapter Two describes the literature review for this study. Review of previous
studies and an overview of plasma antennas, as well as the behavior of plasma
medium are covered. Literatures on plasma antenna technology and reconfigurable
plasma antenna are also included.
Chapter Three provides the methodology of this study including the basic antenna
design structure and the theoretical concept of the antenna in plasma medium. The
method to determine plasma parameter such as plasma density is also presented.
Chapter Four describes an analysis of plasma antenna characteristics by using
discharge tube for different gases. In this chapter, three types of gases which are argon
gas, neon gas and Hg-Ar gas are presented. Different gas pressure settings were used
for different types of analyses. The simulation had been based on the varying gas
pressure settings at 0.5 Torr, 10 Torr and 15 Torr for the three types of gases, while in
experimental the analysis was carried out with sets of gas setting pressure only
8
applicable to argon gas and neon gas, as the Hg-Ar gas was used based on its standard
manufacturing gas pressure. Besides, the results of the comparative analysis, along
with discussions, are also included.
Chapter Five explains the design and the development of the monopole plasma
antenna by using fluorescent lamp at 2.4 GHz for Wi-Fi application. The analysis of
monopole plasma antenna parameter is also presented. Thereafter, comparisons and
discussions between simulation and measurement are covered based on the results.
Chapter Six presents the reconfigurable plasma antenna array. A reconfigurable
plasma antenna was constructed in this research works capable operate at frequency
2.4 GHz. The design and the optimization are thoroughly explained within the
chapter. In addition, the analysis of reconfigurable plasma antenna array is also
presented while the simulation results are compared with the measurement results.
Lastly, Chapter Seven in which some ideas for improvement and possible areas for
future research work and also research contribution are presented.
9
CHAPTER TWO
BACKGROUND AND LITERITURE REVIEW
2.1 INTRODUCTION
Plasma physics is a rapidly expanding field of science. For a long time, it has
coincided with the field of electrical discharges in gases but recently, new fields of
application of plasma physics have appeared. Vital to antenna technology, plasmas are
conductive assemblies of charged and neutral particles and fields that exhibit
collective effects. Besides, plasmas carry electrical currents and generate magnetic
fields. Moreover, combining plasma and antenna in one system is interesting in the
antenna technology. A plasma antenna is a type of antenna in which the metal-
conducting elements of a conventional antenna are replaced by plasma element. This
types of radio antennas that employ plasma element as a radiator for electromagnetic
radiation. Besides, plasma antennas are interpreted as various devices in which plasma
with electric conductivity serves as an emitting element. In plasma antenna the
concept is to use plasma discharge tubes as the antenna elements. When the tubes are
energized, these turn into conductors, and can transmit and receive radio signals.
When de-energized, these revert to non-conducting elements and do not reflect
probing radio signals [16].
This chapter will explain briefly on the overview of plasma antenna. In section
2.2, the fundamental of plasma is covered, and followed by the elementary process in
ionization plasma medium in section 2.3. Next is the method of generating plasma
whereby in this section, divided into two section methods of producing plasma using
electrode and electrode-less. In section 2.5, previous studies and clarification on
plasma antenna technology are explained. This section reviews the previous
researches used for coupling technique in plasma antenna. Meanwhile, the next
section of this chapter explains the shape of plasma antenna and followed by
reconfigurable plasma antenna. Finally, the last section in this chapter depicts the
summary of the application of plasma in antenna technology.
10
2.2 FUNDAMENTAL OF PLASMA
First and foremost, plasma is an ionized gas. Hence, it consists of positive (and
negative) ions and electrons, as well as neutral species. The term plasma is used to
describe a wide variety of macroscopically neutral substances containing many
interacting free electrons and ionized atoms or molecules, which exhibit collective
behavior due to the long-range Coulomb forces. In fact, the word ‘plasma’ derived
from the Greek and it means “something molded”. It was applied for the first time by
Tonks and Langmuir in 1929, to describe the inner region, remote from the boundaries
of a glowing ionized gas produced by electrical discharge in a tube [17].
When a solid is heated sufficiently until the thermal motion of the atoms
breaks the crystal lattice structure apart; usually, a liquid is formed. When the liquid is
heated enough until the atoms vaporize off the surface faster than they recondense, a
gas is formed. Next, when the gas is heated enough that the atoms collide with each
other and knock their electrons off in the process, plasma is formed, the so-called ‘the
fourth state of matter’. Figure 2.1 illustrates the transformation process from solid to
liquid, and next, transforms to gas, and lastly, plasma when heat is increased.
Hence, to demonstrate the transformation towards the fourth state of matter is
best described by taking water (H2O) as an example. Ice represents the solid state of
H2O, in which the molecules of ice are fixed in lattice. The kinetic energy of each ice
molecule is very weak, and therefore, the ice remains in a solid state unless extra
energy is applied. If adequate energy is applied to the ice, the molecules will have
more kinetic energy that allows them to agitate. The extra energy will also cause some
of them to move freely. This condition turns the ice into water (liquid state). If more
energy is applied to liquid, for example by boiling the water, the molecules will have
more energy and get excited. As a result, the molecules are free to move and change
into steam (gaseous phase). In this case, the spacing between each molecule is large
enough compared to its previous states of matter. Since each molecule moves in a
random manner, the kinetic energy for each molecule is different. If the steam is
subjected to thermal heating, illuminated by UV or X-rays or bombardment by
energetic particles, it becomes ionized.
Plasma is not usually made simply by heating up a container of gas. Typically,
in the laboratory, a small amount of gas is heated and ionized by driving an electric
11
current through it or by shining radio waves into it. Generally, these means of plasma
formation give energy to free electrons in the plasma directly and then electron-atom
collisions liberate more electrons and the process cascades until the desired degree of
ionization is achieved.
Figure 2.1 : Change in state of matter [18].
2.3 IONIZATION PROCESS IN PLASMA MEDIUM
Since the plasma is an ionized medium, the key process in plasma is the
ionization process because it is responsible for plasma generation. The simplest of
ionization process is illustrated in Figure 2.2.
Figure 2.2 : Ionization process [19].
A normal atom is electrically neutral because it has the same number of
electrons (particles bearing a negative charge) as protons (particles bearing a positive
charge). Ionization is the process when normal atom becomes a negative ion (anion)
by gaining one or more electrons, or it can become a positive ion (cation) by losing
12
one or more electrons. The process of ionization starts when a sufficiently high
potential difference is applied between two electrodes, the neutral atom is accelerated
by the electric field in front of the cathode and collides with the gas atoms. The gas
atoms will break down and produce electron ions and positive ions. The ionization
degree can vary from 100% (fully ionized gases) to low degree values (partially
ionized).
Figure 2.3 shows an example of ionization process in loop antenna. The plasma
antenna fabricated in [20] is the loop discharge tube that contains a gas, and at the end
of the tube, consists a pair of electrodes. When a gas is excited by applying sufficient
voltage to the electrode, the neutral atom at the electrode will accelerate and collide
with the gas atoms and produce electrons and positive ions, and thus, plasma
formation begins.
Figure 2.3: Ionized plasma at loop antenna [20].
Figure 2.4 shows of electron temperature in electronvolts,eV and electron
densities in (1/m3) for typical of natural and manmade plasmas. Most plasma for
practical significance has electron temperature that ranges from 1 to 20eV with
electron densities in the range from 106 to 10
19 1/m
3.
13
Figure 2.4 : Range of electron temperature and electron density for typical plasma found in
nature and in technological applications [21].
2.4 METHOD OF GENERATING PLASMA
Plasmas can be generated through the application of electric and magnetic
fields, RF heating and laser excitation. Meanwhile, plasma column can be generated
by using such as DC, RF, laser and microwave. The gases that can be used to compose
the plasma are neon, xenon, argon, krypton, hydrogen, helium and mercury vapor. In
general, the formation of plasma can be divided into two groups by using electrode
discharge tube and electrode-less discharge tube. Electrode discharge tube is a tube
that contains gas-filled with the current injected at the electrode while electrode-less
discharge tube is discharge that has no internal electrodes.
2.4.1 Electrode Discharges Tube
Electrode discharge tube is a tube that contains a gas. It is a tube that employs an
electric discharge through a gas as the means of converting electrical energy into light
[16-22]. Figure 2.5 shows the schematic of electrode discharge tube. The two metal
electrodes are cathode and anode. An anode is located at one end while cathode at the
other end. The typically gas-filled in the tube is neon but other gases can also be used.
14
Figure 2.5: A schematic diagram for electrode discharge tube [23].
Plasma is formed when sufficient voltage is supplied between two metal
electrodes in a glass that contains gas [23]. The basic operating mechanism is when an
electric potential volt is applied between the two electrodes [24]. A few electrons are
emitted from the electrodes due to the omnipresent cosmic radiation. Without
applying a potential difference, the electrons emitted from the cathode are not able to
sustain the discharge. However, when a potential difference is applied, the electrons
are accelerated by the electric field in front of the cathode and collide with the gas
atoms. The most important collisions are the inelastic collisions, leading to excitation
and ionization. The excitation collisions, followed by de-excitations with the emission
of radiation, are responsible for the characteristic name of the ‘glow’ discharge. The
ionization collisions create new electrons and ions. The ions are accelerated by the
electric field toward the cathode, where they release new electrons by ion induced
secondary electron emission.
Besides, the electrons give rise to new ionization collisions, creating new ions
and electrons. These processes of electron emission at the cathode and ionization in
the plasma make the glow discharge self-sustaining plasma. The next section, presents
the previous studies that applied electrode discharge tube by using DC and AC.
2.4.1.1 Plasma Generated by using DC and AC
Plasma antenna is a general term that represents the use of plasma as a
conductive medium to transmit or reflect signals. In previous studies, plasma antenna
used 500 MHz 100 W RF power to generate a plasma column, which was limited in
energy efficiency and bandwidth. In paper [25], the researcher implemented DC bias
to generate plasma column as a conductive medium. This paper, which attempted to
develop DC-biased plasma antenna, had no operation frequency for upper limit and
had low sustaining power. Besides, the signal was coupled to the plasma antenna via
capacitive coupling.
15
(a) (b)
Figure 2.6 : (a) The schematic diagram of plasma antenna. (b) The real prototype for plasma
antenna [25].
Figure 2.6 shows the schematic diagram and the real plasma antenna. In this
work, two plasma antennas of 1m and 60 cm in length were built. The plasma antenna
is constructed from 12 mm outer diameter 10 mm inner diameter glass tube, and
inside was filled with Neon gas at 2~5 Torr . The discharge tube that had been
fabricated on both sides of the tube had been two hollow cathode type cylindrical
electrodes. At both electrodes, two wires for DC bias current were connected to a high
voltage power supply. When first turned on, the applied voltage had to exceed the
breakdown voltage of roughly 1.5 KV (for 1m antenna), then the discharge turned into
current control mode at a fixed voltage drop of ~900V. The discharge current ranged
from 5-30 mA at the same voltage drop. The diameter of the positive column was
about 5 mm, whereas the plasma density in the tube was estimated to be about
8.0 1011
cm-3
.
(a) (b)
Figure 2.7: (a) The gain versus frequency curve of metal. (b) The gain versus frequency Neon
plasma antenna [25].
16
(a) (b)
Figure 2.8: (a) The radiation pattern of metal antenna at 8.2 GHz (b) The radiation pattern of
Neon plasma antenna [25].
Figure 2.7 (a) illustrates the gain versus frequency graph for metal antenna,
while figure 2.7(b) shows the gain versus frequency for Neon plasma antenna, at 8.2
GHz. The red curve represented co-polarization, whereas the green (blue) curve was
cross polarization. From this graph, the metal antenna and the Neon plasma antenna
exhibited the same general trend of rising gain after 8 GHz. Figure 2.8 shows the
graph for radiation pattern of metal antenna and Neon plasma antenna at 8.2 GHz
respectively. From this experiment, the radiation patterns of all three antennas were
basically omni-directional.
Usually a gas-filled dielectric tube used with electrode is operated on an AC
supply which is known as fluorescent lamp. Due to its high performance in converting
electrical power to light, size flexibility and good color rendering properties make
them most successful lamp product. Paper [26] depicts a work on fluorescent tube that
performed as a plasma antenna. The AC voltage was applied across the filaments
present at both ends of a tube, and it provided an intense source of electrons. Argon
gas was energized to the plasma state which excited Mercury vapor to radiate UV
rays. The glow due to fluorescence indicated that the Argon gas inside the tube
changed into plasma state and formed the plasma column. Figure 2.9 represents the
plasma antenna by using fluorescent lamp.
Figure 2.10 shows the results of return loss in switch on mode and switch off
mode. In switch on mode, the two most different fluctuating results on network
analyzer were identified, which explained the features of the antenna loss for
fluorescent tube as plasma antenna as shown in Figure 2.10 through ‘B’ and ‘C curves
17
while during switch off mode, the results of return loss showed that there was no
reflection and it means that the fluorescent tube could function as a plasma antenna.
Figure 2.11 illustrates the result for radiation pattern for monopole plasma antenna.
Figure 2.9: The plasma antenna construction [26].
Figure 2.10: Measurement of return loss during switch off mode marked as curve A and
switch on mode marked as curve B and C [26].
18
Figure 2.11: Monopole plasma antenna radiation pattern at 590 MHz. Array 1(red line) is the
co-polarization and Array 2(blue line) is the cross polarization [30].
In paper [27], the plasma antenna used AC driven supply to produce plasma
column. The experimental loop plasma antenna was a commercial annular fluorescent
lamp with a dimension of 100cm in perimeter and 1cm in its cross sectional diameter.
It contained about 0.03Pa of Hg and about 300Pa of Argon.
Figure 2.12: 220V AC-driven plasma antenna [27].
220VAC as well as RF source was fed through the electrodes. In order to
eliminate the antenna effect of wires necessary for 220VAC feeding, ferrite chokes
were employed. A 1:4 transmission line transformer was used as balun to connect the
RF power generator to the antenna. The power scale of the RF generator was about
40W. The system with 220V AC source is depicted in Figure 2.12.
19
2.4.2 Electrode-less Discharge Tube
Meanwhile, an electrode-less discharge tube is a tube that has no internal
electrodes. It was discovered by Hittorf [28] in 1884 and more complete observations
were made soon after by Thomson [29] and Tesla [30]. Electrode-less discharge tube
can be divided into three groups, Capacitively Discharge plasma (CDP), Inductively
Coupled Plasma (ICP) and Microwave Plasma (MP). Table 2.1 shows a detailed
classification of electrodeless lamp based on their discharge mechanism that has
already been discussed in the previous section.
Table 2.1 : Types of electrode less discharge lamps and their applications
Electrode-less discharge type Power Application
CDP 1W~1kW Fluorescent lamp
Facsimile lamp
Excimer lamp
ICP 10W~1kW Fluorescent Lamp
High power UV lamp
Road lamp
MP 1kW~ Photochemistry
HID lamp
2.4.2.1 Capacitively Discharge Plasma (CDP)
Another method to generate plasma column by using electrode-less discharge
tube is capacitively discharge plasma (CDP). CDP can be divided into two categories;
Dielectric Barrier Discharge (DBD) and Capacitively Coupled Plasma (CCP). CDP
discharges are widely used for dielectric etching in the semiconductor industry.
Plasma-generation efficiency (i.e., electron density obtained for a given input power)
improves in CDP with increasing frequency [31]. DBD is characterized by the
presence of one or more insulating layers in the current path between metal electrode
in addition to the discharge space [32]. A basic diagram of DBD is shown in Figure
2.13.
20
Figure 2.13: The common diagram of BDB [32].
An experimental device for DBD generally consists of two parallel electrodes
separated by thin dielectric layer. An AC voltage is applied to the electrodes at a
frequency of several hundred hertz (Hz) to few hundred kilo hertz (kHz). A
breakdown occurs in the gap between the two electrodes at a sufficiently high voltage
enough to ionize the media around. As the charges collect on the surface of the
dielectric, they discharge in microseconds, leading to their reformation elsewhere on
the surface. Plasma is sustained if the continuous energy source provides the required
degree of ionization overcoming the recombination process leading to the extinction
of the discharge. The discharge process causes the emission of an energetic photon,
the frequency and energy of which corresponds to the type of gas used to fill the
discharge gap. DBD devices can be made in many configurations, typically planar,
using parallel plates separated by a dielectric or cylindrical; using coaxial plates with a
dielectric tube between them. Common dielectric materials include glass, quartz,
ceramics and polymers. The gap distance between electrodes varies considerably,
from less than 0.1 mm in plasma displays, several millimeters in ozone generators and
up to several centimeters in CO2 lasers. The purpose of the dielectric barrier is to limit
the electron current between the electrodes.
In paper [33], the dielectric barrier discharge plasma was used to generate a
stable strain of Klebsiella pneumonia (designated to as Kp-M2) with improved 1,3-
propanediol production. The current study aimed to obtain more support for the
positive effect induced by DBD plasma and to generate an excellent industrial strain
of K. pneumoniae for accumulating 1,3-PD. As shown in Figure 2.14, DBD plasma in
air at atmospheric pressure was generated at 20 kHz and 24 kV between a pair of
circular aluminum plate electrodes covered with quartz glasses. A discharge gap of 3
mm between the upper electrode and the surface of the sample suspension was
selected.
21
Figure 2.14: Schematic diagram of the DBD plasma setup. A pair of circular aluminum plate
electrodes was covered with quartz glasses [33].
Capacitively coupled plasma (CCP) is generated with high-frequency RF
electric fields, typically 13.56 MHz. A conventional RF system for sustaining a
discharge consists of a generator and the reactor with electrodes as shown in Figure
2.15.
Figure 2.15: Typical capacitive coupled RF plasma reactor [34].
It essentially consists of two metal external electrodes separated by a small
distance, placed in a reactor. One of the external electrodes is connected to the RF
power supply, and the other one is grounded. As this configuration is similar to a
capacitor in an electric circuit, the plasma formed in this configuration is called
capacitively coupled plasma. CCPs are successfully applied for a wide range of
applications such as deposition of thin-films, plasma etching and sputtering of
insulating materials as well as micro fabrication of an integrated circuit manufacturing
industries for plasma enhanced chemical vapor deposition (PECVD).
In paper [34] presented the formation of plasma using CCP method. As
illustrates in Figure 2.16, a RF power was supplied through a 52 mm diameter
22
stainless steel electrode in CCP configuration. Ring shaped Sm-Co magnets and
cylindrical Sm-Co magnets were mounted in the electrode to form planar magnetron
magnetic field geometry for effective production of high density plasma near the
electrode.
Figure 2.16: The Schematic diagram of experimental apparatus of CCP [34].
2.4.2.2 Inductively Coupled Plasma (ICP)
On the other hand, plasma can be formed by using method inductively coupled
plasma. ICP is an electrode-less discharge where RF power is coupled to the plasma
through a magnetic field. The standard frequency used is 13.56 MHz.
Figure 2.17: Plasma formation by using ICP method [23].
As shown in Figure 2.17 the plasma is induced by coupling the RF energy at
13.56 MHz through a capacitive matching network. The RF current flowing in the coil
generates an RF electric field which accelerates the free electrons causing ionization
and producing the plasma [23]. The time varied magnetic field created by the primary
induction coil which is placed outside the lamp maintains the plasma.
23
2.4.2.3 Microwave Plasma
Plasmas that are created by injection of microwave power, i.e. electromagnetic
radiation can be called as ‘microwave induced plasmas’. The microwave discharge
plasma generated at low pressure has been used in many industrial productions such
as semiconductor and optical component production as a device for etching or
deposition, because it is clean and has high chemical reactivity. It is also being used as
ion production, atomization and light, and excitation source in ion bombardment,
nitrification and solar lamps as well as analytical chemistry, respectively.
The plasma described in [35], uses a microwave plasma generation. In this
paper, the authors developed a plasma source without electrodes. As shown in Figure
2.18, the microwave plasma torch consists of the same magnetrons used in typical
home microwave ovens. The magnetrons used in this study were model number
OM75A. They operated at a frequency of 2.45 GHz and their average power was
about 1 kW. To plasma continuously generate the circuit was modified to full wave
voltage doublers. From Figure 2.18 by injecting swirl gas, the plasma column inside
the discharge tube was more stabilized. Figure 2.19 shows the plasma column when
30 lpm air was injected as a swirl gas.
Figure 2.18 : Schematic diagram to generate plasma [35].
24
Figure 2.19: Plasma column generate using microwave plasma [35].
Meanwhile, paper [36] proposed a new way of producing plasma column by
using microwave and RF discharges based on electromagnetic surface waves to
sustain the discharge. In this way plasma could be driven from only one end of the
column and electrodes should no longer be needed. A plasma column was created by
applying a pump signal to a tube containing a gas; the gas was ionized by a strong
microwave electric field applied at one termination of the tube by a surfaguide device.
The surfaguide launched an azimuthally symmetric electromagnetic surface wave that
propagated along the tube creating and sustaining the plasma column [36]. Figure
2.20 illustrates the longitudinal section of the surfaguide. It consisted of two trunks L0
of a standard waveguide WR340, two transitions L1, and a waveguide L2 with a
reduced height. The guide was terminated by a moving short, whose length Ls could
be varied for matching when the plasma column was turned on.
Figure 2.20: Longitudinal section of the surfaguide. The vertical tube contains plasma to be
ignited [36].
25
2.4.2.4 Radio Frequency (RF) plasma
Meanwhile, as for antenna applications, the plasma must be maintained in
precise spatial distributions such as plasma column. The plasma volume can be
contained in an enclosure (tube) or suspended in free space. Energizing the plasma
column can be accomplished with RF heating, for instance. The paper reported in
[37] presented plasma antenna by using 500 MHz adjustable power RF.
Figure 2.21: Experiment set up for plasma antenna [37].
Figure 2.21 shows the experiment set up for plasma antenna. In this experiment
the system mainly included tuner, power amplifiers, RF source, low-pass filter, power
meter, HF/VHF transmitter, spectrum (noise, and network) analyzer. The gas filled in
the electrode discharge tube was mercury steam and argon. The length was 1.3 m and
the radius was 10 cm, while the coupling ring (used for sending and receiving signal)
was fixed in 15 mm to the top and bottom, and are connected to RF drive pump. From
this experiment, the plasma antenna had wider bandwidth compared to metal antenna
with similar dimensions.
Another plasma formation by using RF was developed in paper [26] .In this
work, monopole plasma antenna was excited by surface wave as shown in Figure 2.22
(a) and (b).
26
(a) (b)
Figure 2.22: The monopole plasma antenna [26].
Figure 2.22 illustrates the experimental set up for monopole plasma antenna.
The plasma was generated by using RF. In this experiment, the gas employed was
hydrogen gas with plasma density estimate equal to 1.5 1020
cm-3
. Besides, this paper
analyzed three-dimensional distributions of electric and magnetic fields around the
monopole plasma antenna. By using Maxwell-Boltzmann equation and applying
molecular dynamic, the related formulas and equations of the model were obtained.
The plasma antenna presented in paper [40] shows the plasma column formation
using RF generator operated at a frequency of 3 MHz to 10 MHz and power up to 100
W.
Figure 2.23: Schematic of plasma antenna [40].
Moreover, a schematic diagram of the experimental setup for generated plasma
column was developed, as shown in Figure 2.23. In this work, the discharge tube was
27
30 cm in length with a diameter 3 cm. The plasma antenna used argon gas as the
plasma medium. Besides, a capacitive coupler width of 35 mm was mounted 2 mm
above the ground plate. From this work, it found that the current on the surface of the
antenna decreased along the axis of the antenna, but it increased with the working
pressure at a particular position and constant input power. The plasma antenna
efficiency was 35% in this experiment. The radiation pattern for plasma antenna and
copper metal antenna was also compared and displayed similar pattern as shown in
Figure 2.24 (a) and (b) respectively.
(a) (b)
Figure 2.24 : (a) The radiation pattern for copper metal antenna. (b) The radiation pattern for
plasma antenna [40].
2.4.2.5 Laser
There are several approaches to creating a plasma antenna. Dwyer et
al.[41]discussed and successful prove that the plasma produced by laser-guided in the
atmosphere has been used as both a transmitting and a receiving antenna. In this
experiment used either a CO2 laser or a glass laser. From Figure 2.25, A1 represents
the plasma antenna being used as the transmitter. As shown in Figure 2.25, the laser
from NL which is a glass laser. The laser passed through a long focal length lens
which is representing L in Figure 2.25. The laser was used to designate the path of the
antenna while an electrical discharge is employed to create and sustain the plasma.
But the laser generates a weakly ionized plasma column, which is then sustained by
the discharge from a Marx generator with a maximum charge of 360 kV. The plasma
produced by a laser-guided, electric discharge in the atmosphere has been formed in
the shape of a folded monopole antenna with a characteristic frequency of 112 MHz.
28
This plasma antenna has been used to transmit and receive signals at 112 MHz.
Researchers at the Naval Research Laboratory have also observed that electric
discharges could be guided in abnormal paths through atmosphere to create desired
antenna geometries through the use of lasers.
Figure 2.25: Schematic diagram of the RF propagation experiment [33].
Another example of plasma generated by a laser is presented in [42]. In this
research, a laser plasma filament was used to produce plasma column which could be
used in passive radar application. Plasma filaments induced by laser would give
propagation of high power femtosecond laser pulses in air and produced great interest,
besides finding many applications in many fields [43] . Figure 2.26 show a virtual
reconfigurable plasma antenna consisting of a set of laser plasma filaments produced
in air by the propagation of femtosecond laser pulses in air. The generated plasma
through filamentation was cold plasma, and thus, it could be suspended in free space
to serve as an antenna [44]. To consider the plasma antenna to behave as an effective
of metal antenna, the plasma frequency must greater than the operating frequency [2-
37]. In this work, the plasma frequency is estimated around 100-300 GHz. Thus it was
better for plasma antenna to operate the frequency at about 30 GHz.
Figure 2.26: Schematic diagram for a proposed Beverage Antenna [42].
29
2.5 PLASMA ANTENNA TECHNOLOGY
The concepts from the combination of plasma technology and antenna
technology have become practical in recent years but the idea is not new. The history
of using ionized gas as a transmitter and receiver was discovered by J.Hettinger in
1919. In his research he suggested that ionized gas (plasma) can be used to transmit
and receive signal [1]. A plasma antenna is a type of radio antenna currently in
development in which plasma is used instead of the metal elements of a traditional
antenna. A plasma antenna can be used for both transmission and reception. Besides,
plasma antenna has attractive features such as by using plasma antennas instead of
metallic elements, they allow an electrical rather than physical control. However, the
development of these antennas poses significant challenges to both antenna designers
and system designers. In this section the overview of previous researches involving
plasma antenna technology is discussed.
2.5.1 Coupling Technique
In order the radiation signal to be transferred to plasma antenna, the signals
should be connected to the tube with a coupler and it is called coupling sleeve. Figure
2.27 shows an example coupling sleeve.
Figure 2.27 :Plasma antenna using coupling technique [46].
Figure 2.27 shows home-made plasma antenna for 5-20 KHz AC with the tube
filled with argon and mercury at working pressure of 5 Torr. The tube with an inner
diameter of 10 mm, an outer diameter of 12 mm and a length of 1200 mm was applied
in this experiment. The shape of the tube was characterized as square-loop, with two
30
electrodes inserted in an insulating box. A coupling sleeve with a width of 30 mm was
placed at the bottom around the tube and was shielded by a well-sealed shielding box
(100 mm 60 mm 60 mm) made of cast aluminum. The coupling sleeve model was
applied to the signal coupling system. The coupler was connected to transmission line
to apply the useful signal. The distance between the center of the coupler and the
electrode was longer than 200 mm.
(a) (b) Figure 2.28: Plasma antenna. (a) Using a standard U-shape fluorescent lamp. (b) Coupling
sleeve [47].
A plasma antenna using U-shape fluorescent lamp is presented in [47] as a
receiver for the standard 88-108 MHz FM radio band. The small RF coupling box
envelopes the lamp as illustrate in Figure 2.28(a). Inside the box is coupling sleeve
which is located at the end of fluorescent lamp as shown in Figure 2.28 (b). As
depicted in Figure 2.28 (a) a BNC connector at the coupling sleeve and coaxial cable
connect to a box containing the FM radio. The RF coupling to the plasma column is
through a metal sleeve surrounding a short length of the tube. This coupling sleeve
provides capacitive coupling for the FM signal from the plasma column inside the
fluorescent tube to the coaxial cable then to the FM receiver
31
Figure 2.29 : Coupling structures. (a) Inductive coupling. (b) Double inductive coupling. (c)
Capacitive coupling [48].
Besides, paper [48] presents a study of several power coupling structures for a
plasma antenna and identified the most effective plasma generation in coupling
technique. Also presented is a study that was undertaken with the aim of identifying
the most efficient way of coupling an information signal for transmission using an
already existing plasma column. The comparison was conducted for three coupling
structures which are inductive, double inductive and capacitive. The coupling
structures are shown in Figure 2.29.
Figure 2.30: Block diagram of the plasma antenna circuit and measurements systems [48].
A similar size of a copper tube was used to substitute plasma column for the
coupling comparison in this paper [48]. The capacitive coupling has significant
capacitance in the circuit. This is because the existence of dielectric tube between the
coupling sleeve and the plasma, whereas with the inductive coupling option, it is
possible that the antenna may not feed effectively off the ground plane. Hence prior to
this comparison, a matching network must be included to ensure that the maximum
32
available power is transferred to the plasma column. Therefore a block diagram of
plasma antenna circuit and measurement system as illustrated in Figure 2.30 was
proposed in [48]. A double stub tuner was used to match the network and a signal
selection is done by a low pass filter.
Figure 2.31: Transmission characteristics (S21) for two type of coupling structures with
different configurations [49].
The comparison results in terms of transmission characteristic (S21) are shown
in Figure 2.31. The findings explained that the double inductive was the least effective
in coupling RF power into the plasma antenna. Longer inductive and capacitive
couplers were found to be more effective than the short ones and these two structures
were equally effective. Besides, the separation gap between the coupling sleeve and
the ground plane had a little effect on the transmission characteristic.
Meanwhile, Figure 2.32 shows examples of capacitive coupling used in paper
[49]. Two coupling sleeves are shown in Figure 2.32, one is used to generate plasma
and the other is used to send information signal in the form of surface wave. A copper
ring was placed around the tube and was soldered to an N-type connector to pump the
excitation of RF energy. A strong electric field was created between the ring and the
ground plane, so that the electric lines penetrated inside the tube, exciting the plasma
column. Another copper ring was mounted to apply the useful signal, using the same
capacitive coupling. These two coupling sleeves were connected to two different
ports.
33
Figure 2.32: Coupling sleeve in an excitation box [50].
Figure 2.33: Coupling between the two ports with (black) and without (gray) the
conducting medium [50].
Figure2.34: Reflection coefficient of the signal port with (black) and without (gray)
the plasma [50].
Figure 2.33 shows the measured coupling magnitude between the two ports
when the plasma is excited. A copper tube is used to simulate the presence of
conductivity. A strong coupling can be seen between exciting port and signal port.
Figure 2.34 describes the measured reflection coefficient, S11 with a similar condition
in Figure 2.33.
34
(a) (b)
(c)
Figure 2.35 : Three different kinds of couplers. (a) Solenoid Coupling. (b) Cubic coupling.
(c) Cylindrical coupling [50].
In paper [50], the authors, analyzed three different kinds of couplers using
CST Studio Suite. The comparison was conducted for three coupling structures which
were solenoid coupling, cubic coupling and cylindrical coupling as shown in Figure
2.35. In this design, a similar size of the fluorescent tube with a radius of 0.016 m was
used. From the analysis, the results for three different couplers showed that, solenoid
coupling was easier to implement but it was not protected from EMI, has bad
reflection coefficient magnitude and the radiation pattern of sample frequency was
broadside with the directivity of 3.44 dB and SLL -13.7 dB. Moreover, cubic coupling
had better results than solenoid coupling, as it is protected from the EMI, has a good
radiation pattern in sample frequency with the directivity of 2.59 dB and SLL -28.2
dB but the implementation of a cubic aluminum around the tube is not so easy and
also as said before it has low frequencies to resonance. Cylindrical coupling is similar
to cubic coupling but it has more frequencies to resonance, easier implementation and
it is more stable if implement it with two bonnets. So the cylindrical coupling is a
35
good way of coupling as the plasma antenna is shielded from EMI, with more
frequencies for resonance and easy implementation but it depends on the application
of the antenna to choose which coupling is better.
2.5.2 Shape of Plasma Antenna
Investigation for plasma antenna radiation pattern for helix shape has been
presented in [51]. Hence, an ideal helix plasma antenna design at target operating
frequency in the UHF band was discovered.
Figure 2.36: The ideal model of plasma helix antenna [51].
Figure 2.36 shows the geometry of the helix plasma antenna. It is assumed
ideally that the plasma is excited at the joint between the plasma tube and the coaxial
line, and the plasma density is uniform among the tube. The length of the coaxial line
above the ground plane is denoted by h. The total height, L, number of turns, N, and
diameter, D of the helix were chose to be 19.08 cm, 4 and 9.54 cm respectively. The
whole antenna was made of a thin tube wire of uniform radius a =0.5 cm. The
diameter of the ground plane was r =12.5 cm, which was approximated to an infinite
conductive plane.
Based on Figure 2.37, the radiation patterns of plasma helix antenna is closer
to the radiation pattern of metallic helix antenna when the plasma frequency is larger
than the operating frequency. Figure 2.38 shows the return loss,S11 of plasma helix
antenna.
36
(a) (b)
Figure 2.37: Comparison results for radiation pattern between metal
antenna and plasma helix antenna. (a) Horizontal plane. (b) Vertical plane [51].
Figure 2.38: Return loss,S11 of plasma helix antenna [51].
Figure 2.39: A model of a plasma whip antenna located on dielectric substrate with relative
permittivity of 2.35 and the thickness, h is 2 mm [52].
Figure 2.39 shows the model of a plasma whip antenna located on the
dielectric substrate with a relative permittivity = 2.35 and a height h =2 mm. The
plasma whip antenna is composed of a glass tube with a relative permittivity of =
37
3.4 and a wall thickness of t = 2 mm. At moderate filling pressure the applied power
will drive noble gas in the glass tube to ionize and form plasma. In this simulation a
plasma rectangular cylinder model is chosen to reduce the staircasing error and the
dimension of the plasma rectangular cylinder is d d l (d = 10mm). The plasma
whip antenna presented in [52] was excited by a coaxial probe with a radius
equivalent to 0.5 mm and the b was about twice of a. Besides, the inner conductor of
the coaxial cable was immediately adjacent to plasma going through the both
dielectric substrate and wall of the glass tube, while the outer conductor was
connected to the ground plane. Figure 2.40, shows the comparison return loss result
between of the plasma whip antenna and metal antenna. It was found that the plasma
rectangular cylinder actually radiated electromagnetic wave as a conducting element.
Figure 2.40: Comparison results of return loss between plasma whip antenna and metal
antenna [52].
A plasma triangular monopole antenna that operate in the VHF band (30-300
MHz) was studied in [53]. The plasma triangular monopole antenna as shown in
Figure 2.41 was simulated using High Frequency Structural Simulator (HFSS). The
simulation results indicated that, when the plasma frequency was sufficiently higher
than the operating frequency and the collision frequency was corresponding low, the
plasma antenna could operate with characteristics similar to a metal antenna. Besides,
the peak gain of plasma antenna was lower than the metal, in operating bend angle
range.
38
Figure 2.41 : A plasma triangular monopole antenna [53]
2.5.3 Reconfigurable Plasma Antenna
Reconfigurability, when used in the context of antennas, is the capacity to
change an individual radiator’s fundamental operating characteristics through
electrical, mechanical, or other means [54], [55]. Reconfigurable antennas have
attractive features such as the ability to reconfigure themselves autonomously to adapt
to the changes or with the system to perform entirely different functions.
Recently there has been interest in the use of plasmas as the conductor for
antennas, as opposed to the use of metals. Plasma can be rapidly created and destroyed
by applying electrical pulse to the discharge tube. Hence plasma antenna can be
rapidly switched on and off. When it is off, it is non-conducting and invisible to
electromagnetic radiations. When it is on, plasma becomes a good conductor. The
plasma is highly conducting and acts as a reflector for radiation for frequencies below
the plasma frequency [56]. Besides, due to their unique properties plasma antenna can
be applied as a radiation pattern reconfigurable antenna.
A reconfigurable plasma antenna presented in [57] was made of a 30 cm long
plasma column which acted as a plasma antenna. The gas filled was argon gas. The
operating parameters such as working pressure and radius of glass tube will be
changed to transformed single plasma antenna to array plasma antenna as shown in
Figure 2.42 (a) and (b).
39
(a) (b)
Figure 2.42 : Plasma antenna. (a) Single plasma antenna. (b) Array plasma antenna [57].
By changing the operating parameters, single plasma antenna can be
transformed into multiple antenna elements which are arranged in even numbered
series (4, 6, 8, 10 and 12). The length and the numbers of plasma column can be
controlled by the operating parameters such as input power and working pressure.
From this work, the directivity of antenna increased when the number of plasma
element increase. Figure 2.43 illustrates the radiation pattern between single and array
plasma antenna. The red line represents radiation pattern array plasma antenna while
the black line represents radiation pattern single antenna.
Figure 2.43 : Comparison between normalized elevation radiation patterns of single and array
plasma antenna [57].
Another work that is relate to reconfigurable plasma antenna is presented in
[3]. The experimental setup of plasma antenna is shown in Figure 2.44. The discharge
tube was made from borosilicate (Pyrex) glass with a length 30 cm, while the diameter
was 3 cm.
40
Figure 2.44 : The schematic diagram of plasma antenna [3].
From this paper, the plasma antenna was transformed from the single plasma
antenna into array, helical and spiral plasma antenna. Figure 2.45 shows the helical
plasma antenna filled with argon gas. It was observed that when changing the working
pressure from 0.03 to 0.050 mbar (0.0225 to 0.0375 Torr), the single plasma antenna
could be transformed to array plasma antenna and when the working pressure was
increased, the plasma antenna changed to helical plasma antenna and then spiral
plasma antenna.
Figure 2.45 : The helical plasma antenna [3].
On top of that, with monopole plasma antenna the reconfigurable
characteristics can be realized under certain condition [5]. The radiation parameters
for the plasma antenna array can be reconfigured through changing variable
parameters of the plasma elements. To produce monopole plasma antenna, equipment
such as discharge tube, RF power source and coupling device will be used. The
experimental is illustrated in Figure 2.46. Meanwhile, as shown in Figure 2.47(a) from
41
experiment, the length of plasma column had been shorter when the driven power was
15 W compared to plasma column in Figure 2.47(b) which was driven when power
was 39 W. When the power increased, the plasma density also increased, so it could
produce a good plasma column [58].
Figure 2.46 : The diagram of experimental setup [5].
(a) (b)
Figure 2.47: (a) The plasma column when driven power is 15 W. (b) The plasma column
when driven power is 39 W [5].
Numerical calculations results demonstrated that when the excitation power is
small, plasma density is not high; the reconfigurable properties of radiation pattern are
unobvious. This work showed that if the plasma density increased, the radiation
pattern was changed apparently with the increase of plasma density and excitation
power.
42
Figure 2.48: Plasma reflector antenna installed in anechoic chamber [59].
In addition, plasma can reflect the signals whose frequency is lower than
plasma frequency while it will be transparent when the operating frequency is higher
than plasma frequency [45]. From these advantages, the plasma antennas are highly
reconfigurable and can be turned on and off. From this theory in paper [59], the
plasma antennas used 17 commercially available fluorescent light tubes, with a
nominal projected tube to tube spacing of 1.5 inches was designed. The length of the
fluorescent light was 33.5 inches. The prototype of this antenna is shown in Figure
2.48. The radiation pattern shown in Figure 2.49 for plasma is quite similar with its
metal counterpart. It can be seen that when the plasma is de-activated, the reflected
signal is dropped by over 20 dB. These two scenarios have confirmed that the plasma
reflector antenna is able to give similar performances as metal reflector.
Figure 2.49 : Radiation Patterns of Plasma Reflector Antenna and Metal Reflector Antenna
[59].
43
Figure 2.50: Geometry of reconfigurable plasma corner reflector antenna [60].
This research presents simulation and experimental results in order to verify
the performance and the radiation patterns of a reconfigurable plasma corner reflector
antenna. Three different beam shapes were offered alternately. The reconfigurable
plasma corner reflector antenna elements were made of a series of fluorescent lamps
that were coordinated in a V arrangement as illustrated in Figure 2.50. The half-
lambda distance of s= 0.5 required eight elements, while the lambda distance of s =
1.0λ required 16 elements for both reflector sides. The realized model was fabricated
on a 3 mm thick ground plane as shown in Figure 2.51.
Figure 2.51 : The 24 plasma elements for reconfigurable plasma corner reflector antenna
with a monopole antenna in the center of the ground plane [60].
44
(b)
Figure 2.52: Normalized H-plane radiation patterns. (a) Simulation. (b) Measurement [60].
The evolution of a single shape radiation pattern can be changed into a dual-
beam shape as shown in Figure 2.52. Unlike the omni-directional beam shape, the
single beam shape could be formed by switching ON all plasma elements with s equal
to 0.5λ, while elements with the s equal to 1.0λ are switched OFF. If doing otherwise,
double-beam shapes will show up. If all elements are switched ON, the single beam
remains without allowing the double beams to emerge. This is an alternative to form
single-beam shape.
2.6 SUMMARY
In this chapter, the basic of plasma such as fundamental of plasma and
ionization process has been explained in detail. From the previous study shows that
ionization process is important to generate plasma and to act as a conductor element.
In addition, this chapter summarize from previous study method of generating plasma
and plasma antenna technology including method of coupling sleeve, shape of plasma
antenna and reconfigurable plasma antenna. The plasma antennas described in this
chapter represent a selection of examples found in a review of the literature. Generally
in current electronic communications industry requires high performance and efficient
systems to meet the demands of today are continuously evolving applications.
Physical limitations of microwave devices and circuits have stalled further
improvements of current technology. In the midst of this scenario, the usage of plasma
as conductive element in microwave devices has drawn growing interest due to their
peculiar and innovative properties with respect to the traditional metallic circuits.
From previous studies, highly ionized plasma is essentially a good conductor and
45
therefore, plasma filaments can serve as transmission line elements for
electromagnetic wave transmission and reception. Besides, plasma antennas use
plasma elements instead of metal conductor. They are constructed by an insulating
tube filled with low pressure gases. The plasma rapidly created and destroyed
applying proper radio frequency (RF) power pulses to the discharge tube so that the
antenna is switched on and off. When the antenna is on, it exhibits a high
conductivity, providing a conducting medium for the applied RF signal. The main
advantage in using plasma antennas instead of metallic elements is that they allow an
electrical rather than mechanical control. The conceptual structure of the proposed
plasma antenna is demonstrated and discussed in more detail in the next chapter.
46
CHAPTER THREE
RESEARCH METHODOLOGY
3.1 INTRODUCTION
The number of industrial applications of plasma technologies is extensive and
involves many industries including material processing, environmental control and
communication system. In antenna application, plasma permits antenna structures to
be reconfigurable with respect to shape, frequency, band- width, directivity and gain
on millisecond to microsecond time scales. As a result, plasma may be able to form
viable antenna array elements that weigh less and require less space than metal
structures. When plasma is highly ionized, it essentially becomes a good conductor,
and therefore plasma medium can serve as transmission line elements for guiding
waves, or antenna surfaces for radiation. In the midts of this scenario, the usage of
plasma as a conductive element in microwave devices has drawn growing interest due
to their peculiar and innovative properties with respect to the traditional metallic
circuits. Besides, the term ‘plasma antenna’ has been applied to a wide variety of
antenna concepts that incorporate the use of an ionized medium. In vast majority of
approaches, the plasma, or ionized volume, simply replaces a solid conductor.
This research focused on the development of antenna using plasma medium as
a conductor element instead of using a metal element. Prior to that, the methodology
of the research, which was divided into three stages, is presented in this chapter. The
flowchart of each stage is included in the first section. Next, the fundamental of
plasma parameter in plasma physics in described in section 3.3. Before the plasma
antenna was designed, the estimation of plasma parameters, such as plasma frequency
and collision frequency, were determined, as explained in section 3.4. Meanwhile, the
fabrication and the measurement setup are presented in section 3.6, and followed by a
summary in section 3.7.
47
3.2 RESEARCH METHODOLOGY
The research had been divided into three main stages. In the stage 1, a
cylindrical monopole plasma antenna using argon gas, neon gas, and Hg-Ar gas
(mixture of argon gas and mercury vapor) was successfully designed and simulated. In
this stage, the aim was to analyze the interaction between plasma parameter and
antenna performance. A literature review on the interaction of plasma element with
electromagnetic waves antenna was done in first stage. Moreover, analysis process on
the effects of different gases and different pressures with regard to antenna
performance based on the simulation results had been investigated.
In stage 2, the monopole plasma antenna using fluorescent lamp for Wi-Fi
application was successfully developed. The investigation on several properties of the
antennas that included the effect of coupling sleeve in plasma antenna was also
reviewed in this stage. Comparison and analysis of different parameters of antenna,
such as the length of plasma antenna and the diameter of plasma antenna, are
presented in this stage.
In stage 3, a development process of reconfigurable plasma antenna array was
successfully developed. The aim target in this stage was to develop a reconfigurable
antenna for beam steering, which was capable in steering 360 degrees of beam
scanning by using plasma element instead of metallic element. The reconfigurable
plasma antenna array used the fluorescent lamp as the plasma element. In order to
reconfigure the radiation patterns of the antenna, the performances of the antennas on
plasma activated (switched ON) and de-activated (switched OFF) states were
investigated in this stage, and the analysis of the antenna performances is presented in
this stage. The design was continues with 2.4 GHz for Wi-Fi application with
optimization on monopole antenna as a radiation signal. After meeting the objectives
as mention in chapter 1, the real product was fabricated, and next, was implement with
switching system by using Arduino technology.
In this research, Computer Simulation Software (CST) Microwave Studio was
employed to design and simulate the proposed antenna in each stage. Meanwhile, the
switching circuit was designed and simulated by using Arduino Technology. The
simulated results were optimized until the best results were obtained with the
consideration of the effects on antenna gain, reflection coefficient, Voltage Standing
48
Wave Ratio (VSWR), main lobe direction and operating frequency. The simulated
antenna designs from stage 1 to stage 3 had been successfully fabricated and measured
using laboratory test equipment such as vector network analyzer to validate the
proposed topology and its synthesis. The flow of the research methodology for stage 1
to 3 illustrated in Figure 3.1(a), (b) and (c) respectively.
49
(a)
Start
Problem Statement and
Objectives
Literature review on the
interaction of plasma medium
with electromagnetic waves
and plasma antenna technology
Design, simulation and
optimization of the cylindrical
monopole plasma antenna using
argon gas, neon gas and Hg-Ar gas
NO
YES
NO
YES
Meet the
spec?
Fabrication, measurement and analysis of the antenna
Meet the
objectives?
End
50
(b)
End
YES
YES
NO
NO
Start
Problem statement and objectives
Literature review on
fluorescent tube as a plasma
antenna and coupling sleeve
method
Design, simulation and
optimization of the monopole
plasma antenna using fluorescent
tube with coupling sleeve at 2.4
GHz
Meet the
spec?
Fabrication, measurement and analysis of the antenna
Meet the
objectives?
51
Figure 3.1: Flow chart of the research. (a) Stage 1- cylindrical monopole plasma antenna.
(b) Stage 2 - monopole plasma antenna using fluorescent lamp.
(c) Stage 3- reconfigurable plasma antenna array.
YES
YES
(c)
Start
Problem statement and objectives
Literature review on
reconfigurable plasma antenna
array
Design, simulation and optimization
of reconfigurable plasma antenna
array
Meet the
spec?
Fabrication and integration with Arduino system
measurement and analysis of the antenna
Measurement and analysis of the antenna
Meet the
objectives?
End
YES
NO
YES
NO
52
3.3 FUNDAMENTALS PARAMETERS OF PLASMA PHYSICS FOR PLASMA
ANTENNA
Plasma is a dispersive material that offers particular electrical properties when
electromagnetic waves are applied to it. As a frequency dependent material, it also has
these properties; electrical conductivity and electrical permittivity. These electrically
controlled properties allow for the exploration of plasma as one of the material options
in designing antennas. Hence, by understanding the relationship between plasma
medium and incoming electromagnetic waves, it may lead to a promising
development of plasma antennas.
Plasma medium can be a good conductor when it is highly ionized and from
this concept, the plasma medium can replace the metallic medium. Plasma filaments
can serve as transmission line elements for guiding waves, or antenna surfaces for
radiation. Therefore, it is necessary to understand the interaction between plasma
medium and electromagnetic waves. The following section explains plasma properties
and its relation with electromagnetic waves.
The plasma medium is complicated in that the charged particles are both
affected by external electric and magnetic fields, as well as contribute to them.
Nonetheless, the resulting self-consistent system is nonlinear and very difficult to
analyze. Furthermore, the inter-particle collisions, although also electromagnetic in
character, occur on space and time scales that are usually shorter than those of the
applied fields or the fields due to the average motion of the particles. Therefore, to
make progress with such a complicated system, various simplifying approximations
are needed.
The explanation is started with consideration of a single particle motion model
under the effect of electromagnetic field. The plasma derived in the following section
is with an assumption of homogenous plasma.
3.3.1 Plasma Frequency
One must distinguish between plasma frequency and the operating frequency of
the plasma antenna. The plasma frequency is a measure of the amount of ionization in
the plasma and the operating frequency of the plasma antenna is the same as the
operating frequency of a metal antenna. The plasma frequency of a metal antenna is
53
fixed in the X-ray region of the electromagnetic spectrum whereas the plasma
frequency of the plasma antenna can be varied.
Being a medium of free charge carriers, plasma exhibits natural oscillations
that occur due to thermal and electrical disturbances. The derivation starts with
assumption on the harmonic oscillations of electrons around the ions. Due to harmonic
oscillation the electron density can oscillate at an angular frequency ωp , and so the
resulting electric field intensity E will oscillate at the same frequency [61]. The
density oscillations give rise to a net free charge density ρ which is related to volume
current density J as [62]:
3. 1
Which is called the Continuity Equation. Taking J =σE ,
3. 2
The net free charge density ρ is related to the electric field intensity as
3. 3
Thus, equation 3.1, 3.2 and 3.3 are combined,
3. 4
The free charge density ρ becomes
3. 5
The contribution of ions to the plasma frequency was assumed neglect. When
ion oscillation takes place within a shorter span than electrons, the electrons get
heavier. Thus, the volume charge density expression in equation 2.5 can be assumed
to depend only on oscillation of electron. Thus, the solution to the differential
equation above is
3. 6
The angular frequency of oscillation of the free charge density ρ is also ,
thus, the plasma frequency is
54
3. 7
Besides that, from the volume of current density in the plasma the plasma
frequency also can be derived due to electromagnetic wave interactions,
3. 8
3. 9
Thus the plasma frequency is depicted in equation 3.7. By substituting the
numerical values of the parameters, the plasma frequency is
= 8.94 3. 10
Where:
= Electron density
= 1.60217653 x 10-19
C is the electron charge,
= 9.1093826 x 10-31
kg is the electron mass.
= 8.8541878 x 10-12
Free space permittivity
3.3.2 Plasma Collision Frequency
In studying plasma behavior, one of the plasma parameters that need to be
identified is plasma collision frequency. Knowledge of the dependence of the
effective electron-neutral collision in noble gas, such as argon, is very important in
order to understand many of the plasma processes, especially for its fundamental and
applications. This type of collision frequency is often referred to evaluate the energy
transfer between particles. The collision frequency that occurs in gases is important in
radio frequency field.
55
Consider a gas consisting of elastic hard spheres of type 1 into which a test
particle of type 2 with velocity v is introduced. Both species of particles share similar
radius a. The test particle will collide with particle of type 1 and cylinder container
with a cross-sectional area σ. In a time interval t, a test particle with a velocity v
covers a distance vt along this cylindrical volume of length, vt and cross section σ as it
collides with other particles. If there are particles of type 1 per unit volume, the
number of collision on the cylinder by the test particle is equal to the product of this
number density and the volume of the cylinder.
3. 11
The velocity v in equation (3.11) is usually given by a Maxwellian distribution,
and the cross section σ is often velocity dependent. These velocity dependences are
accounted for by defining an energy-dependent reaction rate coefficient [21] :
3. 12
Where is the Maxwellian distribution as shown in equation 3.13
3. 13
Equation 3.12 implies averaging σ over a Maxwellian distribution. Thus the
number of collision per unit time or collision frequency, is,
1/s 3. 14
Where :
= Collision frequency
= Electron density
σ = Collision cross section
= electron speed
56
3.3.3 Conductivity of the Plasma Medium
Conductivity of plasma medium is the most important parameter in plasma
antenna. The charged particles that constitute the plasma will be under the effect of
the Lorentz force when interacting with an electromagnetic wave. Firstly, consider
this charged to be an electron, q where this particle must follow the Lorentz force
which is known as momentum conservation equation [62]:
3. 15
Where q is the charge of the particle, v is the velocity of the particle, E and B
are the electromagnetic and magnetic fields influencing the particle. For this initial
analysis, it will be assumed that there is no static external electric and magnetic fields.
If we take a transverse electromagnetic wave as in free space, the E and B fields are
3. 16
3. 17
Where is the free space permeability constant and is the intrinsic wave
impedance of free space. Consider only in time dependence of the fields, in the
electric and magnetic field expressions is omitted as if it is included in the term.
The term
can be rewritten as
3. 18
Where c is the speed of light in free space. Thus B can be expressed as
3. 19
Hence, the resultant acceleration of the particle is
3. 20
Writing the acceleration and velocity in differential form and substituting
equation 3.12 and 3.13 in equation 3.16, the equation become:
57
3. 21
Meanwhile, the acceleration components can be written as:
3. 22
3. 23
3. 24
From the above equations the velocity components for a charges particle can
be obtained. Assume
<< c, the velocity component of the particles along the
direction of propagation is smaller than the velocity of light, thus:
3. 25
The velocity and displacement in the x-direction can be written as
3. 26
3. 27
From the formulation above, the integration constants are neglected, which are
related to mean position and velocity of the charged particle during one period. By
substituting equation 3.26 in 3.24,
3. 28
3. 29
3. 30
58
From the above equation, acceleration, velocity and position components of
the particles are all periodic. This implies that the mean position, energy and velocity
of particles are all constant for each period. By calculating the velocity components; it
is now possible to express the volume of the current density induced within the plasma
by the electromagnetic wave. The current density can be written as
3. 31
Where is the electron volume density of the plasma and is the electron
charge. In the above equation, it is assumed that the current flow is only in the x-
direction, since the velocity of particles in the z-direction is negligible. Besides, the
contribution of ion flow in the current density is neglected when the ion mass is
greater than the electron mass. The particle mass term in the denominator of velocity
expressions makes the velocity of ions smaller than electron velocity, making the
contribution of ions negligible. In terms of electric field strength, the volume current
density can be expressed directly as a:
3. 32
From equations 3.31 and 3.32, as well as substituting the velocity expression
from equation 3.26,
3. 33
Where is the electron mass and is the electron volume density of the
plasma. From the equation above, the conductivity of plasma medium can be
expressed as
3. 34
Equation 3.34 is the conductivity equation for plasma medium in terms of
particle charge, mass and density.
Let’s consider the effect of collision process with an assumption that the
electrons lose all its energy during collision. Since only a collision less single-particle
model was assumed in the beginning of the derivation, with the effect of collision (the
in previous equations is now to represent more than one particle involved in
the collisional case), Equation 3.15 now becomes
59
3. 35
With an introduction of as a collision frequency and if time dependence
is assumed, then the left-hand side of equation 3.35 turns out to be
3. 36
From this result, the can replace by
in equation 3.34 in order to
include and consider the effect of collision frequency. Therefore, the conductivity is
3. 37
and if one assumes that there is only DC electric field and unmagnified plasma
(isotropic cases) ,the conductivity of plasma medium is :
3. 38
From the expression it is observed that conductivity depends on the collision
frequency of the plasma. As the collision frequency increases, the conductivity
decreases due to the σ inversely proportional to the in the expression. This
dependence of conductivity on the electromagnetic wave frequency is of great
importance for the plasma antenna concept; while physical parameters of the plasma
are determined based on the working frequency of the plasma antenna.
3.3.4 Complex Dielectric Permittivity of the Plasma Medium
From equation 3.38, the complex permittivity of the plasma medium can be
derived. The propagation constant of the electromagnetic wave in a conducting media
can be obtained from the wave equations:
3. 39
3. 40
The solutions to the wave equations are:
3. 41
60
3. 42
Where η is the intrinsic wave impedance of the medium and k is the
propagation constant. Substituting equation 3.41 in equation 3.39 the expression
becomes
3. 43
Since
the t term in parentheses is the complex permittivity which
is
–
3. 44
And the propagation constant is
3. 45
From the above equation, the propagation constant depends on the relation
between plasma frequency and wave frequency.
3.4 ESTIMATION OF PLASMA AND COLLISION FREQUENCY
Before proceeding with designing the plasma antenna, two most important
parameters, which are plasma frequency and collision frequency, need to be
determined. These two parameters have a very significant influence in plasma antenna
behavior if wished to be design. A computer coding program characterizing the
characteristic of plasma medium is presented in [63] . Certain parameters, such as the
type of gas, radius of discharge tube, discharge current, gas fill temperature, and gas
pressure, have to be determined to run this program. Prior to this, an experiment has to
be conducted in order to obtain all the required parameters values. This program will
first calculate the electron density of the gas inside the discharge tube and from the
electron density, the values of plasma frequency and collision frequency can be
determined from equations 3.10 and 3.14. Figure 3.2 below shows the flow chart of
GLOMAC program (is a computer code for describing low pressure gas such as
61
electron density and electron temperature) that requires data obtained from the
experiment to be inserted in.
Figure 3.2 : Flow diagram of GLOMAC to calculate electron density for argon and neon
gases.
Set the gas ratio value for gas
Insert measured tube radius value
in cm
Insert value for discharge current
in Ampere (A)
Insert value for gas pressure in
Torr
Insert gas fill temperature in
Celsius
Insert the cold spot temperature
value in Celsius
Insert the positive column (PC) in
cm
Insert cathode fall value (V)
Insert wall axis temperature value
in Celsius
62
Figure 3.3: Flow diagram of GLOMAC to calculate electron density for mixture of argon and
mercury vapor.
First and foremost, the type of gas to be used was determined and the ratio of
gas filling was set. In this research work, three different gases; argon, neon, and Hg-
Ar (can be found inside fluorescent lamp) were used. As for argon and neon gases, the
Set the gas ratio value for gas
Insert measured tube radius
value in cm
Insert value for discharge current
in Ampere (A)
Insert value for gas pressure in Torr
Gas pressure = Argon gas pressure + mercury vapor pressure
Set argon gas
pressure 5 Torr
Calculate mercury
vapor pressure
Insert gas fill temperature in
Celsius
Insert the cold spot temperature
value in Celsius
Insert the positive column (PC)
in cm
Insert cathode fall value (V)
Insert wall axis temperature
value in Celsius
63
gas ratios were assumed and set to be 1.0, while for the Hg-Ar gas, the ratio was
assumed 0.9 for Argon and 0.1 for mercury [64].
Next, measure the radius of discharge tube in centimeter (cm). Then, get the
value of discharge current by measuring the current flowing through the discharge
tube. After that, set the value of gas pressure. Gas pressure values for argon gas and
neon gas inside the discharge tube are known from an experimental work done by a
researcher, Dr Ahmad Nazri Dagang at the Energy Conversion Laboratory, Faculty of
Engineering, Ehime University, Japan. While for fluorescent lamp, there is no
variation for the values of plasma parameters as they are fixed by design.
Specification details on fluorescent lamp are limited and kept confidential by the
manufacturer. Thus, experimental works need to be conducted in order to obtain the
gas pressure value inside fluorescent lamp.
Gas pressure of fluorescent tube is a combination of two types of pressure,
which are vapor pressure of mercury (need to be calculated) and Argon gas pressure
(standard range 0.1-10 Torr, and 5 Torr was assumed in this experimental work) [65].
While for vapor pressure of mercury, a few steps were performed to obtain vapor
pressure value. First, measure the outer wall temperature of the fluorescent tube with a
portable digital thermometer TFN520 after the tube has been switched on and let it
stabilize for about 15-30 minutes. Then, add the measured temperature with the delta
obtained from the formula presented in appendix D (Refer appendix D). The sum of
delta T and measured temperature is herein taken as the temperature inside the lamp.
After that, the obtained temperature inside lamp was compared with data for
temperature versus vapor pressure from appendix E (Refer appendix E) In addition;
interpolation was performed to retrieve the exact mercury vapor pressure value. The
value of gas pressure inside the fluorescent lamp is the summation between mercury
vapor pressure value and Argon gas pressure.
Then, the gas fill temperature for the program was set to be equal to room
temperature at 230C. After the gas fill temperature was set, the cold spot temperature
was obtained. This was done by measuring the temperature at three points, which
were at both end and middle of the fluorescent tube. The highest temperature is known
as Tcmax, while the lowest value as Tcmin .
64
Next, the length of PC and the cathode fall were determined for the fluorescent
tube. The PC length represents the positive column of the fluorescent tube. It is a
length measured from one end of an electrode inside the fluorescent tube to another
electrode end (Refer appendix A). After that, a cathode value was required for this
program. The formula to obtain the cathode fall value is presented below:
Vk = V- Vp 3. 46
Vp= EpLp 3. 47
Where:
Vk : cathode fall voltage
V : lamp voltage
Vp : voltage of positive column
Ep : electric field at positive column (for Hg fluorescent lamp is about 1V/cm)
Lp : length of positive column
3.5 DRUDE DISPERSION MODEL FOR DESIGNING PLASMA
The behavior of the plasma is given by drude dispersion model in CST
software. The drude dispersion model describes the simple characteristic of an
electrically conducting collective for free positive and negative charge carriers, where
thermic movement of electrons is neglected. Figure 3.4 shows the graphical user
interface for drude dispersion model in CST software.
Figure 3.4: Defining a plasma in CST [66].
The plasma frequency ωp and the collision frequency νc are called drude
parameters. ɛ∞ is the relative dielectric constant at infinite frequency, generally ɛ∞ =1
The value of plasma frequency and collision frequency are obtained from equation
65
3.10 and 3.14 Plasma frequency is a natural frequency of the plasma and is a measure
of the amount of ionization in plasma. One must distinguish the difference between
the plasma frequency and the operating frequency of the plasma elements. The plasma
frequency is a measure of the amount of ionization in the plasma, while the operating
frequency of the plasma elements is similar to the operating frequency of a metal
antenna.
3.6 FABRICATION AND MEASUREMENT SETUP
In this section, the fabrication process for the designed plasma antennas and
the set up for the measurement process are discussed briefly.
3.6.1 Fabrication process
As mentioned in the previous chapter, the objective of this research was to
focus on the interaction between RF and plasma medium. Thus, to look more into the
mechanism of interaction between them, three fabrication processes were carried out.
This section begins with the fundamental laboratory setup. It was necessary to
produce plasma column as a conductor medium. The setup consisted of a vacuum and
gas filling system, which was constructed with a vacuum pump, rotary pump, burner,
pressure gauges, gas container, and piping lines. This setup was necessary to produce
electrode-less discharge tubes for plasma discharge. Next was the construction of
monopole plasma antenna using fluorescent tube, while the last part was fabrication
for reconfigurable plasma antenna using low cost plasma, which was fluorescent tube.
3.6.1.1 Cylindrical Monopole Plasma Antenna Using Electrode-less Discharge Tube
The discharge tube used in this work was a glass from glass borosilicate
(Pyrex) with the length (LA) of 160 mm inner and outer diameters of 9 mm (DI ) and
10 mm, (DO) respectively as described in Figure 3.5(a). Besides, three types of gases
were filled in this tube; argon gas, neon gas and Hg-Ar gas. For argon gas and neon
gas the gas pressure is applicable at pressure 0.5 Torr, 5 Torr and 15 Torr
respectively while for Hg-Ar gas the commercially fluorescent lamp is used as a
cylindrical monopole plasma antenna. Figure 3.5 shows the real electrode-discharge
tube. Due to lack of materials and setup in ARG, the electrode discharge tube was
66
specially ordered and fabricated at the Energy Conversion Laboratory, Faculty of
Engineering, Ehime University, Japan.
Moreover, as mentioned in the previous section, plasma can be produced by
using Capacitively Discharge Plasma (CDP), Inductively Coupled Plasma (ICP) and
Microwave Plasma (MP). CDP can be divided into two categories; Dielectric Barrier
Discharge (DBD) and Capacitively Coupled Plasma (CCP). However in this
research, DBD method is used to generate the plasma. Dielectric-barrier
discharge (DBD) is the electrical discharge between two electrodes separated by an
insulating dielectric barrier.
Figure 3.5(b) shows the experiment setup for DBD method. The electronic
ballast was used to energize the plasma column with the specification of output up to
1kV, 50-60 Hz .The electronic ballast was connected to the DC power supply, while
the coupling sleeve was connected to the feeding line with a 50 Ω SMA connector. On
the other hand, a 20 GHz Vector Network Analyzer was connected to the SMA
connector to couple the signal to the plasma column of the plasma antenna. The
aluminum tape with a length of 100 mm and a width of 5 mm was fastened at the
discharge tube. The aluminum tape functioned as external electrodes. When sufficient
voltage was supplied between the two aluminum fasteners, the electron gas inside the
discharge tube was accelerated by the electric field and produced ions, which is called
ionization process, as mentioned in chapter two. Glowed tube indicated that the gas
inside the tube was ionized to plasma and formed a plasma column. Figure 3.6 and
Figure 3.7 show the glowed tube for neon and argon gases discharge tube at pressures
15 Torr.
67
(a)
(b)
Figure 3.5 : Monopole plasma antenna using electrode-less discharge tube. (a) Schematic
diagram. (b) Construction of monopole plasma antenna.
Figure 3.6 : Photograph of neon gas discharge tube at 15 Torr.
68
Figure 3.7: Photograph of argon gas discharge tube at 15 Torr.
3.6.1.2 Monopole Plasma Antenna Using Fluorescent Tube
The plasma antenna was constructed using a commercially available
fluorescent tube with 589.8 mm length (LFT) and 28 mm of diameter (DFT) that works
as radiating element in this study. The gas inside the fluorescent tube was a mixture of
argon and mercury vapor. Figure 3.9 (b) represents the construction of the plasma
monopole antenna. The tube was energized by electronic ballast with specification of
220.240 V, 50-60 Hz. Meanwhile, the AC power supply which was provided by a
standard AC power supply was connected to electronic ballast before it was directed
to both electrodes of the fluorescent tube. Electronic ballast was more preferred
compared to magnetic ballast because electronic ballast is lighter in weight than
magnetic ballast and more it had been proven to be more efficient compared to
magnetic ballast. The function of ballast is to stabilize the current through the tube.
Glowed tube indicated that the gas inside the tube was ionized to plasma and formed a
plasma column. In this state, the plasma column became highly conductive and could
be used as an antenna. For the coupling sleeve as shown in Figure 3.8, the position at
the lower end of the tube as an input terminal, this is used to connect the plasma tube
with external signals and measuring equipment. Copper wire with 5 numbers of turns
is used and the end of copper wire is connected to SMA connector. The aluminum
tape with length of 30 mm and width of 18 mm is wrapped at copper wire. The
schematic diagram for monopole plasma antenna is illustrated in Figure 3.9 (a).
69
Figure 3.8 : Position of coupling sleeve.
(a)
(b)
Figure 3.9: Monopole plasma antenna using fluorescent tube. (a) Schematic diagram. (b)
Construction monopole plasma antenna.
Figure 3.10 illustrates a monopole plasma antenna integrated with 3G Wi-Fi
router. In this research work, a monopole plasma antenna using fluorescent tube was
designed at frequency 2.4 GHz, which was suitable for Wi-Fi application. For
70
monopole plasma antenna to function as a Wi-Fi system, the antenna must be
integrated with Wi-Fi wireless and router. This monopole plasma antenna was
equipped with access-point 3G Wi-Fi router, which was installed inside the casing of
the fluorescent tube. The Wi-Fi router was connected to the RF signal. Meanwhile, the
function of the dongle was to supply 3G input signal. The RF signal supplied from the
router passed through a 50 Ω cable and combined with the plasma element inside the
fluorescent tube through coupling sleeve. The RF signal and the 3G input, which were
injected to the plasma element, made this antenna to function as Wi-Fi technology. In
addition, the Access Point Router (AP Router) was modified by removing the
available printed antenna and replacing it with the constructed monopole plasma
antenna. Hence, in order to ensure that the monopole plasma antenna could transmit
and receive the signal, several measurement tests were performed.
Figure 3.10 : Monopole plasma antenna integrated with 3G Wi-Fi router.
Figure 3.11 : Monopole plasma antenna integrated with 3G Wi-Fi router during switch ON.
3.6.1.3 Reconfigurable Plasma Antenna Array
Cylindrical-shaped fluorescent tube type T5 was used as reflective elements
and coordinated in circular arrangement. The total number of fluorescent tubes used in
the simulation was 12. The height of each element from ground plane surface was 288
71
mm, the diameter of the lamp is 16 mm, and the central monopole height was 35 mm
with a diameter of 3 mm. On top of that, the angle between the centers of two adjacent
elements was 30°.
(a) (b)
Figure 3.12 : Geometry of reconfigurable plasma antenna array (a) Side view (b) Top view.
The realized model was fabricated on 3 mm thick ground plane based on the
geometry depicted in Figure 3.12. The fabricated prototype is shown in Figure 3.13
(c). The top and the bottom parts of the reconfigurable plasma antenna array prototype
are made from a type of polymer known as Nylon. Nylon was chosen in this design
because of its natural behavior that cannot radiate the RF signal. In addition,
excitation power to energize the 8 Watts fluorescent tubes was supplied by a set of
electronic ballasts with specification of 220-240 V, 50-60 Hz. The AC power supply
was connected to the electronic ballast before it was directed to both electrodes of the
fluorescent tube. Each of the electronic ballast was controlled by a small single-pole
switch. Each setup of electronic ballast required a set of four wires to be connected to
each fluorescent tube. In overall, the design of this antenna had 12 electric ballasts and
12 switches as shown in Figure 3.13 (a) and (b).
72
(c)
Figure 3.13: Prototype of reconfigurable plasma antenna array. (a) 3D AutoCAD drawing. (b)
Connection of 1 of fluorescent tube. (c) Prototype of reconfigurable plasma antenna array.
Moreover, the electric ballast was chosen instead of magnetic ballast as the
element to energize fluorescent tube due its simplicity, less noise, and compact in size.
The fluorescent tube was fixed at the bottom of the ground plane and was carefully
glued to the ground plane. The gluing process was done one by one for the rest of the
fluorescent tubes. The fluorescent tubes had to be in vertical alignment with respect to
73
the ground plane surface. Besides, the fluorescent tube was connected from the top
electrode to the bottom electrode by using wires, which were hidden inside in the
support holder. The support holder was made of Polyvinyl chloride (PVC).
Meanwhile, the monopole antenna, which was located at the center of the fluorescent
tube with a diameter of 3 mm, as shown in Figure 3.13 (a), was connected to the
feeding line with a 50 Ohm SMA female connector.
3.6.2 Measurement setup
To ensure that the antenna met the specifications and to test if the antennas
functioned, antenna measurements were needed. In this section, the steps of measuring
the antenna are presented.
3.6.2.1 Return Loss Measurement
The measurements for S11 and radiation pattern for all prototypes in this
research had been conducted in the Antenna Research Centre, Faculty of Electrical
Engineering. In addition, the calibration process was also done prior to each
measurement to ensure the accuracy of the results. The vector network analyzer
(VNA) consisted of two outputs. As depicted in Figure 3.14, the antenna under test
(AUT) was directly connected to the VNA using output 2. This had been because; at
that moment, output 1 experienced malfunction issue. The measurement results from
the VNA were compared with the simulation results and the graphs were plotted by
using SigmaPlot 10.0 software.
Figure 3.14 : Setup for return loss measurement.
74
3.6.2.2 Radiation Pattern Measurement
The measurement of antenna radiation patterns was done in an indoor anechoic
chamber located at the Chamber Room of Antenna Research Centre, Faculty of
Electrical Engineering, Universiti Teknologi MARA using the near-field measurement
system. Figure 3.17 illustrates the arrangement of radiation patterns measurement in
the indoor anechoic chamber. The chamber consisted of an azimuth turn table and a
transmitter (TX) antenna on the polarization positioner. During measurement, the
antenna under test (AUT) was placed on the azimuth turn table so that the AUT would
be rotated based on the desired cut-plane. The distance between AUT and TX antenna
was approximately 1 m. Moreover, the indoor anechoic chamber was linked with the
measurement room where the equipment for radiation patterns measurement was
located. The measurement equipment included a positioned controller signal
generator, a spectrum analyzer, and control PC with antenna measurement software.
The actual view of the indoor anechoic chamber and the measurement equipment are
shown in Figures 3.15 and 3.16, respectively.
Figure 3.15 : The radiation patterns measurement setup and the actual inside view of the
anechoic chamber room.
75
Figure 3.16: The radiation patterns measurement setup and equipment for radiation patterns
measurement.
Figure 3.17 : The layout of the measurement setup for radiation pattern measurement.
3.6.2.3 Radiation Signal Measurement
In this experiment the main objective is to prove that the received signal is
transmitted from plasma antenna and not from coupling sleeve. The coupling sleeve
was covered with aluminum shielding box with dimensions 52 mm 55 mm as
illustrates in Figure 3.18 and Figure 3.19. The main function of aluminum-wrapped
shielding box was to enclose the radiation generated by coupling sleeve from radiated
out from the box. In this experiment, the Wi-Fi router was ON and has been set to the
76
minimum transmission power. The signal strength of the monopole plasma antenna
has been measured in three conditions; first is in condition where coupling sleeve was
uncovered with aluminum-wrapped shielding box and fluorescent tube was switched
ON, second coupling sleeve was covered with aluminum-wrapped shielding box and
fluorescent tube was switched ON, third is coupling sleeve was covered with
aluminum-wrapped shielding box and fluorescent tube was switched OFF. Results of
these three conditions will be discussed and explained in chapter 5.
Figure 3.18: Coupling sleeve is wrapping with aluminum shielding box. (a) Left view. (b)
Right view. (c) Bottom view. (d) Top view.
Figure 3.19 : Coupling sleeve is wrapping with aluminum shielding box. (a) Front view
during fluorescent tube switched OFF. (b) Front view during fluorescent tube switched ON.
77
3.6.2.4 Measurement of Radiation Signal from Monopole Plasma Antenna as a
Transmitter
Figure 3.20 : Experimental setup for plasma antenna that serves as a transmitter.
The plasma antenna was connected to an RF signal generator through the
coupling sleeve. The RF signal generator was set to generate a continuous wave at 2.4
GHz. Besides, when excited by this alternating current, the antenna radiated radio
waves and acted as a transmitter. Apart from that, a reference metal monopole antenna
was used as the receiving antenna, and the signal captured by receiver was observed
using a spectrum analyzer. The spectrum analyzer was used to measure the captured
frequency and the power density of each frequency component. The distance, d,
between transmitter and receiver was 1 m. Then, the experiment was preceded with
RF generator in the turn off mode, and the results were compared and discussed in
Section 5.6.1 of chapter five. Figure 3.20 represents the experimental setup for plasma
antenna that served as a transmitter.
3.6.2.5 Measurement of Radiation Signal from Monopole Plasma Antenna as a
Receiver
Figure 3.21: Experimental setup for plasma antenna that serves as a receiver.
d=1m
78
In this experiment, the plasma antenna was connected to the spectrum analyzer
through the coupling sleeve, and served as a receiver instead. The reference metal
monopole antenna was connected to the RF signal generator and served as a
transmitter. The RF signal generator was set to generate signal in a similar frequency
range as conducted in the previous experiment. The distance, d, was also fixed at 1 m.
The signal transmitted from RF generator was captured by plasma antenna and was
measured using the spectrum analyzer. Then, similar measurements were done when
the plasma antenna was de-energized and was removed from the receiver system.
Figure 3.21 represents the experimental setup for plasma antenna as a receiver.
3.6.2.6 Measurement of Signal Strength Monopole Plasma Antenna
In antenna, the signal strength at a specific point can be determined from the
power delivered to the transmitting antenna. This signal strength can be observed
using a Wi-Fi analyzer, which is software that can be installed on the smart phone.
Wi-Fi analyzer is one the applications on the Android system which was used to
observe the signal strength of Wi-Fi channels on the wireless router. In this research
work, the monopole plasma antenna served as a transmitter at a distance of 3 meter as
shown in Figure 3.22.
Figure 3.22: Testing the signal strength of monopole plasma antenna.
3.7 SUMMARY
In the beginning of this chapter, a brief review of research methodology has
been discussed. Elaboration pertaining to the fundamental parameters of plasma was
also given. In this work, in order to determine the plasma parameters, such as plasma
79
frequency and collision frequency, the software GLOMAC was used. Besides,
experimental approach was adopted to retrieve some values of parameters. After
obtaining the plasma parameters, the plasma antenna was designed using the Drude
model in Computer Simulation Software (CST) Microwave Studio.
The methods used to develop and to measure plasma antenna performances are
also presented in this chapter. The plasma antenna for cylindrical monopole plasma
antenna using discharge tube and monopole plasma antenna with fluorescent tube
utilized the plasma as the radiating element, while for reconfigurable plasma antenna
array using fluorescent tube used plasma element as a reflecting elements. To
construct the monopole plasma antenna using fluorescent tube and reconfigurable
plasma antenna array using fluorescent tube, the available fluorescent lamps in the
market were used. Based on this concept, the design of plasma antenna is further
described in detail in the next chapter.
The performance of the defined plasma model is measured and explained in
the following chapter. The similarity between the measured and the simulated results
is reconfirmed in the defined plasma model.
80
CHAPTER FOUR
A CHARACTERICTICS OF CYLINDRICAL MONOPOLE
PLASMA ANTENNA
4.1 INTRODUCTION
In this present study, the analysis of cylindrical monopole plasma antenna for
electrode-less discharge tube by using CST microwave studio was carried out, as it
has not been established yet. Experiments performed before have verified that
monopole plasma antenna possessed many properties similar to monopole metallic
antenna. When the tubes of plasma antenna were energized, they were turned into
conductors, and could transmit and receive radio signals. When de-energized, these
revert to non-conducting elements and failed to reflect probing radio signals [37].
These make plasma antenna to have more unique properties compared to metallic
elements, as they allow electrical rather than physical control. However, for plasma
antenna to behave like a conducting element, some parameters, such as pressure of
gases and type of gases, are necessary and need to be identified for antenna
performances.
This chapter discusses the analysis for the characteristics of cylindrical
monopole plasma antenna and three different gases with three different pressures
which were argon gas, neon gas and Hg-Ar gas (a mixture of mercury vapor argon
gas) that employed plasma as its radiating element. In this experiment for argon gas
and neon gas, cylindrical monopole plasma antennas were fabricated using glass
borosilicate (Pyrex) with a dielectric permittivity = 4.82 and a length of 160 mm,
diameter of 10 mm and thickness of 1 mm. Meanwhile, commercial fluorescent tube
was used for Hg-Ar experiment. The glass material that use in commercial fluorescent
tube was borosilicate (Pyrex) [67]. The discharge tubes were filled with argon gas and
neon gas at pressures of 0.5 Torr, 5 Torr and 15 Torr. A brief description on electrode-
less discharge tube is given in section 4.2. In this work, the Dielectric Barrier
Discharge (DBD) method was used to produce the plasma. The experiment setup was
described in chapter 3. Moreover, the design procedure using CST microwave studio
81
is presented in section 4.3 too. The effect of plasma frequency on propagation of
electromagnetic wave is explained in section 4.4. Besides, an analysis on cylindrical
monopole plasma antenna design, which included two cases of different pressures and
different gases, is described in section 4.4. Based on analysis, the frequency at 4.6
GHz because of the limitation and unavailability of material and technology to
produce discharge tubes. However, based on literature review, 4.6 GHz frequency will
produce the same concepts analysis as 2.4 GHz frequency. The simulation and the
measurement results of cylindrical monopole plasma antenna are presented in section
4.5, and followed by a summary in section 4.6.
4.2 ELECTRODE-LESS DISCHARGES FOR DIELECTRIC BARRIER
DISCHARGE
An electrode-less discharge is a discharge that has no internal electrodes in
which the power required to generate plasma is transferred from outside the discharge
tube to the gas inside via an electric or magnetic field. Capacitively Discharge Plasma
(CDP) is one of type mechanism to generate plasma using electrode-less discharge.
CDP can be divided into two categories which is Capacitively Coupled Plasma (CCP)
and Dielectric Barrier Discharge (DBD). In this work, the DBD method was chosen
because of it is easier and simpler to setup the experiment and cheaper to generate the
plasma.
A dielectric barrier discharge (DBD), is one of the most common types of
industrial plasma sources. It was discovered by W. Siemens in 1857 for the purpose of
"ozonizing" air DBDs have for a long time been regarded as the ozonizer discharge
[68]. DBD devices can be made in many configurations, typically planar, using
parallel plates separated by a dielectric or cylindrical, using coaxial plates with a
dielectric tube between them. It essentially consists of two electrodes separated by a
small distance of a dielectric material. Typical voltages applied to the electrodes vary
from hundreds to thousands of volts. A basic circuit diagram of DBD is shown in
Figure 4.1. When an electric field is generated between two external electrodes (such
as aluminum tape), electrons in the gas respond to the field and acquires energy while
the ions, being heavier and acquire less kinetic energy compared to electrons. The
high-energy electrons can ionize the gas directly or indirectly by collisions thus
82
producing secondary electrons. When the electric field is strong enough, it can lead to
what is known as an electron avalanche and the gas becomes electrically conductive
due to abundant free electrons. The excitation and ionization processes are repeated
and plasma is produces and sustained.
Figure 4.1: A simple schematic diagram of a capacitive discharge [33].
4.3 DESIGN OF CYLINDRICAL MONOPOLE PLASMA ANTENNA
As mentioned in the previous section, the main objective of this chapter had
been to analyze the characteristic of interaction between plasma medium and RF
microwave. Three types of gases were utilized; argon, neon, and Hg-Ar (a mixture of
mercury vapor and argon gas) gases with 0.5 Torr, 5 Torr, and 15 Torr respectively.
The design of the cylindrical monopole plasma antenna with different gases and
pressure is explained in detail. In addition, the characteristics of the varying pressures
and gases are analyzed in this section.
4.3.1 Design Procedure
To simulate the performance of a plasma monopole antenna design, CST
MWS software was used. Before the antenna was designed, the plasma properties,
such as plasma frequency and collision frequency, were inserted first in Drude
dispersion model in CST software. The Drude dispersion model describes simple
characteristics of an electrically conducting collective of free positive and negative
charge carriers, where thermic movement of electrons is neglected. The values of
plasma frequency and collision frequency can be obtained from equations 3.10
(plasma frequency) and 3.14 (collision frequency) in chapter 3 and the electron
density can be determined by using GLOMAC software as explained in chapter 3.
83
4.3.2 Structure of Cylindrical Monopole Plasma Antenna
Figure 4.2 shows the dimensions of the cylindrical discharge tube that was
used in the experiments. The tube was 160 mm in length, while the inner and the outer
diameters were 9 mm and 10 mm respectively. The glass material was borosilicate
(Pyrex) with a dielectric constant 4.82 and aluminum tape was used to fasten both
opposite sides of discharge tube as an energy transfer medium. Function of aluminum
tape as an external electrode to generate plasma column. Besides, a coupling sleeve
was positioned at the lower end of the tube and the Vector Network Analyzer was
connected between the coupling sleeves and the discharge tube. Number of turns of
coupling sleeve is four [69]. Figure 4.3 shows the real prototype of cylindrical
monopole plasma antenna. In simulation there was no need to design the aluminum
tape because in CST Microwave studio, plasma could be generated by using the drude
model. Table 4.1 summaries the parameters of a cylindrical monopole plasma antenna.
Figure 4.2: The schematic diagram of discharge tube.
Figure 4.3: Discharge tube used in this experiment.
Table 4.1:
The parameters of a cylindrical monopole plasma antenna
Parameter Label Diameter(mm)
Length of discharge tube LA 160
Outer diameter of discharge tube DO 10
Inner diameter if discharge tube DI 9
a
84
Distance coupling sleeve at the bottom
of discharge tube
LB 10
4.4 ANAYLSIS OF CYLINDRICAL MONOPOLE PLASMA ANTENNA
In this section, the analyses for three types of gases, which were Argon, Neon,
and Hg-Ar gases are presented. Every gas consisted of pressures 0.5 Torr, 5 Torr, and
15 Torr respectively. The reason this research used these three gases had been because
they were inexpensive materials. Besides, the effects of the plasma parameters were
analyzed to identify if plasma medium could function as a conductor element.
4.4.1 Effect of Plasma Frequency on Complex Permitivity
In general, plasma frequency determines if the plasma medium can act as a
metal or an absorber. One of the electrical properties of a medium that is important in
applications of electromagnetic is electrical permittivity. With this parameter known,
propagation of electromagnetic waves in plasma medium can be inspected thoroughly.
Theoretically, the plasma possesses some conduction properties. When the plasma
frequency is higher than the electromagnetic wave frequency (ωp >ω), the
electromagnetic wave will be reflected as the plasma behaves as a conductor and it
can be used to radiate radio signal. Nonetheless, when the plasma frequency is lower
than the electromagnetic wave frequency (ωp<ω), the electromagnetic wave radiation
passes through the plasma and the plasma becomes transparent. The electrical
conductivity of plasma determines how good the plasma is if it is meant to radiate
radio signals. In other words, the electrical conductivity of plasma plays a major role
whenever plasma is used as a radiator. In plasma, the imaginary part in complex
permittivity represents losses in the medium and the real part indicates the energy
stored in the medium ( ’-j ”) [71-72]. Based on equation 3.45, permittivity depends
on plasma frequency, electron density, and microwave frequency.
In this section, the analysis of complex permittivity for cylindrical monopole
plasma antenna conductivity for Argon, Neon, and Hg-Ar gases was looked into with
pressures 0.5 Torr, 5 Torr, and 15 Torr.
85
(a)
(b)
86
(c )
Figure 4.4: Relative Permittivity for argon gas, neon gas and Hg-Ar gas for (a) 0.5 Torr (b) 5
Torr and (c) 15 Torr.
Figure 4.4 illustrates the plasma complex permittivity based on Drude model
for argon gas, neon gas and Hg-Ar gas at pressures (a) 0.5 Torr, (b) 5 Torr and (c) 15
Torr respectively. From the graph, the value of imaginary increases when the
operating frequency is decreased while the real part becoming more negatively when
the operating frequency decreased thus loss in plasma will increase for three gases.
Meanwhile, as for Hg-Ar gas at 0.5 Torr as a plasma antenna, the operating frequency
must greater than 1 GHz (>1 GHz). This because from the Figure 4.4 (a) shows that
when the operating frequency is less than 1 GHz (< 1 GHz) the loss in plasma is
increase while for Argon gas and Neon gas the starting operating frequency that
suitable to act as a plasma antenna at frequency 2 GHz (>2 GHz).
On the other hand, Figure 4.4 (b) portrays that the loss for Hg-Ar gas is
extremely slow at frequency range >1.8 GHz at 5 Torr. For Argon gas the loss began
to decrease at an operating frequency of >3 GHz, while for Neon gas, the loss occur
when the operating frequency below than 2 GHz at pressure of gas at 5 Torr.
Apart from that, Figure 4.4(c) clearly shows that Hg-Ar gas the loss extremely
slow at operating frequency > 2 GHz for pressure 15 Torr. However, for Neon gas and
Argon gas the loss started to decrease at operating frequency >6 GHz for pressure 15
Torr.
87
4.4.2 Effects of Different Pressures
Relationship between plasma parameter and radio frequency waves were
explained in detail in this section. The effect of different pressures for same gas were
investigated and analyzed. The analysis was cover for reflection coefficient, VSWR,
gain, directivity and radiation pattern.
4.4.2.1 Argon Gas
In the periodic table, argon is a one of the noble gases and it is in group 18.
Incandescent lights are filled with argon to preserve the filaments at high temperature
from oxidation. It is used for the specific way it ionizes and emits light, such as
in plasma globes and calorimeter in experimental particle physics. Gas-discharge
lamps filled with argon provide the color light blue.
Figure 4.5: The effect on reflection coefficient, S11 for different pressure for Argon gas.
In this case, the effect of different pressure for Argon gas on reflection
coefficient, S11 has been investigated. As for cylindrical monopole plasma antenna at
operating frequency 4.6 GHz , the reflection coefficient, S11 for pressure 0.5 Torr is -
26.43 dB , 5 Torr is -28.15 dB and 15 Torr is -32.35 .The design of the antenna is
portrayed in Figure 4.2. As depicted in Figure 4.5, it clearly shows that the different
pressure has significant effect on reflection coefficient, S11. It can be seen that the
pattern for return loss shifted to the downward at the operating frequency of 4.6 GHz
when the pressure is increase. From numerical calculation of GLOMAC as explained
88
in chapter 3, the electron density,ne for 0.5 Torr, 5 Torr and 15 Torr; ne = 8.12 1017
m-3
, ne = 7.54 1018
m-3
and ne = 1.23 1019
m-3
respectively.
Figure 4.6: The effect on VSWR for different pressure for Argon gas.
Meanwhile, Figure 4.6 shows the effect on VSWR for different pressure with
the same gas. From the graph, the VSWR for three different pressures show below
than 2 at operating frequency of 4.6 GHz. The value of VSWR indicates how well an
antenna is matched to the cable impedance where the reflection, |Γ| = 0. This means
that all power is transmitted to the antenna and there is no reflection. Although the
optimal value of VSWR is 1, it must be lower than 2 so that the antenna yields a
return loss of more than 10 dB [71].
Figure 4.7: Comparison of different pressure for Argon gas radiation patterns in polar-plot.
The radiation pattern in polar plot for Argon gas at pressures 0.5 Torr, 5 Torr
and 15 Torr have been compared at operating frequency 4.6GHz. The radiation pattern
89
is referred at E-plane (phi=90o). As clearly shown in Figure 4.7, they are similar in
shape. The results indicate that at main lobe direction, 0.5 Torr Argon have the highest
gains as compared to the 5 Torr and 15 Torr. The gain for 0.5 Torr is equal to 4.638
dBi while for 10 torr and 15 torr are 4.604 dBi and 4.458 dBi respectively. Hence, this
analysis proved that, when the pressure is increase, the gain wills decrease. It is due,
when the pressure increase, the collision will increase as well. The collision
frequency,νc for 0.5 Torr is 1.59 109 1/s, 5 Torr = 2.113 10
10 1/s and 15 Torr =
6.338 1010
1/s. From equation 3.38 the collision frequency, νc is inversely
proportional to the plasma conductivity,σ. When collision frequency increase, the
plasma conductivity,σ will decrease. The plasma conductivity,σ which was obtained
from equation 3.38 showed that at pressure 0.5 Torr, σ = 14.99 S/m, 5 Torr, σ = 10.07
S/m and 15 Torr, σ = 5.48 S/m. Hence, it can influence the value of gain antenna.
Table 4.2 shows the summary of simulation comparison results for antenna
performances.
Table 4.2:
The performance of cylindrical monopole plasma antenna using argon gas
Pressure(torr) Reflection
coefficient,S11(dB)
VSWR Plasma
conductivity
(S/m)
Gain(dBi) Directivity(dBi)
0.5 -26.43 1.10 14.99 4.638 5.419
5 -28.15 1.08 10.07 4.604 5.452
15 -32.35 1.05 5.48 4.458 5.486
4.4.2.2 Neon Gas
Neon is the second-lightest noble gas, after helium. It is in group 18 (noble
gases) in the periodic table. Neon is used in vacuum tubes, high-voltage
indicators, lightning arrestors, wave meter tubes, television tubes, and helium–neon
lasers. Besides, neon has been used to build plasma antenna since it is inexpensive.
90
Figure 4.8: The effect of reflection coefficient,S11 for Neon gas at different pressure.
Figure 4.8 shows the comparison of simulated reflection coefficient, S11 for
Neon gas at pressures 0.5 Torr, 5 Torr and 15 Torr at an operating frequency of 4.6
GHz. From Figure 4.8, the reflection coefficient, S11 at pressure 0.5 Torr is -25.32 dB,
5 Torr is -27.41 dB and at 15 Torr is -32.34 dB. It clearly shows that the pattern of
return loss is slightly similar to Argon gas, whereby the pressure increase as the
resonant frequency shift to the downward. By using GLOMAC software, the value of
electron density,ne at pressure 0.5 Torr is 4.04 1017
m-3
, 5 Torr is ne = 4.30 1018
m-
3 and 15 Torr is ne = 9.96 10
18 m
-3.
Figure 4.9: The effect of VSWR for different pressure for Neon gas.
As depicted in Figure 4.9, the VSWR for three different pressures for Neon
gas have been compared. From the figure, the VSWR all the three different pressures
are below than 2 at frequency 4.6GHz and show that the antenna is well matched to
the cable impedance where the reflection is =0.
91
Figure 4.10: Comparison of different pressure for Neon gas radiation patterns in polar-plot.
Figure 4.10 illustrates the simulated results of radiation pattern in polar plot at
E-plane (phi=90°) for three different pressures for Neon gas at a frequency of 4.6
GHz. The results show that the radiation patterns of monopole plasma antenna using
neon gas as a plasma medium look similar with each other. The pattern gain for Neon
gas is almost similar with the argon gas. It can also be noted from Figure 4.10, that
antenna gain generated by 0.5 Torr is 4.803 dBi higher than 5 Torr (4.717 dBi) and 15
Torr (4.550 dBi). Meanwhile, the collision frequency, νc at pressure 0.5 Torr is νc =
6.87 108 1/s, 5 Torr is νc = 1.10 10
10 1/s and 15 Torr νc = 3.474 10
10 1/s. By
using equation 3.38, plasma behaves as a metal when plasma conductivity,σ for 0.5
Torr, 5 Torr and 15 Torr obtained are σ = 16.59 S/m, σ = 11.02 S/m and σ = 8.10 S/m
respectively. Figure 4.10 describe from simulation result, when increase the pressure,
the gain will decrease. This because from equation 3.38, the plasma conductivity,σ
will decrease when collision frequency increase. Thus the gain of cylindrical
monopole plasma antenna also decreases. Table 4.3 summarizes the simulation results
for 0.5 Torr, 5 Torr and 15 Torr respectively for neon gas.
92
Table 4.3:
The performance of cylindrical monopole plasma antenna using neon gas.
Pressure(Torr) Reflection
coefficient,S11(dB)
VSWR Plasma
Conductivity
(S/m)
Gain(dBi) Directivity(dBi)
0.5 -25.32 1.11 16.59 4.803 5.502
5 -27.41 1.09 11.02 4.717 5.509
15 -32.34 1.05 8.10 4.550 5.544
4.4.2.3 Hg-Ar gas
Most of the discharge lamps in use at the present time are the mercury-argon;
Hg-Ar gas fluorescent lamps. Their high performance in converting electrical power
to light, size flexibility, and good color rendering properties make them the most
successful lamp product. Light is mainly produced by conversion of short wavelength
UV radiation to visible radiation with the phosphor coating on the inner wall of the
tube.
A typical hot cathode fluorescent lamp consists of a glass tube with its inner
surface coated with fluorescent powder. It is filled with argon gas, a drop of mercury,
and the filaments are tungsten wire electrodes coated with a thermionic emitter sealed
into each end of the tube [72]. The rare gas argon is added to the lamp primarily to
assist starting since the vapor pressure of mercury is very low initially.
Figure 4.11: The effect of reflection coefficient,S11 for different pressure for Hg-Ar gas.
Figure 4.11 illustrates the comparison of simulated results for reflection
coefficient, S11 when the pressure varied from 0.5 Torr until 15 Torr for Hg-Ar gas.
93
From the graph it clearly shows that when the pressure is increased, the resonant
frequency 4.5 GHz shifted to the downward. The value of reflection coefficient, S11 at
pressure 0.5 Torr is S11= -29.04 dB, 5 Torr is S11 = -31.19 dB and 15 Torr is S11= -
37.20 dB. The electron density, ne obtained for 0.5 Torr is ne = 1.13 1018
m-3
, 5 Torr
= is ne = 7.92 1018
m-3
and 15 Torr is ne = 1.61 1019
m-3
.
Figure 4.12: The effect of VSWR for different pressure for Hg-Ar gas
Figure 4.12 clearly shows the simulation results for VSWR for different
pressure for fluorescent tube. At frequency 4.5GHz, the VSWR of plasma antenna
with pressure 0.5 Torr, 10 Torr and 15 Torr is 1.07, 1.06 and 1.03 respectively.
Figure 4.13: Comparison of different pressure for Hg-Ar gas radiation patterns in polar-plot
As depicted in Figure 4.13, the radiation pattern for cylindrical monopole
plasma antenna using Hg-Ar gas at three different pressures look similar to ideal
94
monopole antenna. The radiation pattern also will change with the variation of
pressure in monopole plasma antenna. From figure 4.14, the gain is increase when the
pressure is decrease. The simulated peak gain yield at 0.5 Torr is 3.075 dBi while for
10 Torr and 15 Torr are 2.662 dBi and 15 Torr 2.171 dBi respectively. Meanwhile,
plasma conductivity,σ obtained from equation 3.38 shows that the value of σ = 13.57
S/m at pressure 0.5 Torr, σ = 9.58 S/m at pressure 5 Torr and σ = 4.89 S/m at pressure
15 Torr, As mentioned before this, the plasma conductivity,σ is inversely proportional
to the collision frequency. From of Hg-Ar pressure, 0.5 Torr νc = 2.35 109 1/s, 5
Torr νc = 2.33 1010
1/s and 15 Torr νc = 9.28 1010
1/s. When increase the pressure
the collision frequency also increase and as a results the plasma conductivity will
decrease. Hence, the performance of antenna in terms of gain will decrease.
Table 4.4:
The performance of monopole plasma antenna using Hg-Ar gas.
Pressure(Torr) Reflection
coefficient,S11(dB)
VSWR Plasma
Conductivity
(S/m)
Gain(dBi) Directivity(dBi)
0.5 -29.04 1.07 13.57 3.075 3.110
5 -31.19 1.06 9.58 2.662 2.722
15 -37.20 1.03 4.89 2.171 2.718
4.4.3 Comparison of Different Gases Performance
In this section, the effects of different gases were analyzed and compared. The
characteristics of the three different gases such as return loss, VSWR, plasma
conductivity, gain, directivity and radiation pattern, are presented in this section.
95
(a)
(b)
(c)
Figure 4.14: The effect of reflection coefficient,S11 for different gas at (a) 0.5 Torr (b) 10 Torr
and (c) 15 Torr.
Figure 4.14 shows the simulated reflection coefficient,S11 for Argon gas, Neon
gas and Hg-Ar at (a) 0.5 Torr, (b) 5 Torr and (c) 15 Torr. From the Figure 4.14(a)
when pressure is fix to 0.5 Torr the resonant frequency for fluorescent tube is slightly
shifted to the right (4.5 GHz) compared to Argon gas and Neon gas which is the
resonant frequency for both are at 4.6 GHz. Besides, the reflection coefficient, S11 is
measured at 4.6 GHz for Argon gas and Neon gas at pressure 0.5 Torr are -26.43 dB
96
and -25.32 dB respectively during simulation while for Hg-Ar at frequency 4.5 GHz is
-29.04 dB. For pressure 5 Torr the reflection coefficient, S11 for Argon gas and Neon
Gas at frequency 4.6 GHz are -28.15 dB and -27.41 dB respectively. For Hg-Ar at
resonant frequency 4.5 GHz the of reflection coefficient, S11 is -31.19 dB. Moreover,
when the operating frequency at 4.6 GHz for Argon gas and Neon gas at pressure 15
Torr the reflection coefficient, S11 are -32.35 dB and -32.34 dB respectively while for
Hg-Ar the reflection coefficient, S11 is -37.20 dB at 4.5 GHz.
The reflection coefficient,S11 for Argon gas and Neon gas is look similar to
each other. This might be because Argon and Neon gases are noble gases and are
positioned in the same group in the periodic table. The same pattern of reflection
coefficient, S11 is clearly shown at Figure 4.14 (b) and Figure 4.14 (c) when the
pressure at 5 Torr and 15 Torr. Besides, the results from the analysis of VSWR for
different gases of cylindrical monopole plasma antenna are depicted in Figure 4.15.
The simulated VSWR for different gases is below than two and indicates that the
cylindrical monopole plasma antenna is matched to the transmission line and the
power is delivered to the antenna.
(a)
97
(b)
(c)
Figure 4.15: Comparison of simulated VSWR for different gases at (a) 0.5 Torr (b) 5 Torr and
(c) 15 Torr.
The radiation patterns of antenna for different gases are illustrates in Figure
4.16. From the Figure 4.16 it clearly shown that the pattern of radiation pattern for
Argon and Neon gases look similar at pressure 0.5 Torr, 5 Torr and 15 Torr. Based on
these results, at pressure 0.5 Torr, 5 Torr and 15 Torr, Neon gas achieved higher gain
compared to Argon gas and Hg-Ar gas.
As can be seen from the tables 4.5, 4.6 and 4.7, the antenna gain increases
correspond to the increment of plasma conductivity values. The value of antenna gain
compared to type of gases is in order of Ne > Ar > Hg-Ar at all for different pressures.
Neon shows the highest value of antenna gain while Hg-Ar shows the lowest. Even
though the values of collision frequency is in order of Hg-Ar > Ar > Ne, which means
more collision should be occurred in Hg-Ar and Ar tubes compared to Ne tube.
However, when look at the size and mass of atom/molecule, the order is Hg-Ar
> Ar > Ne, where neon is the lowest in terms of size and mass. For Hg-Ar gas:
98
(atomic no: 80, atomic mass: 200.6 u, atomic radius: 171 pm), for Argon gas: (atomic
no: 18, atomic mass: 39.95u, atomic radius: 71pm) and for Neon gas: (atomic no: 10,
atomic mass: 20.18u and atomic radius: 38pm) [73-74]. When the size is big it is easy
for the atom to collide with the surrounding particles due to its high surface area to
volume ratio. In contra, when the mass of atom is high, the collision that occurred will
give less impact due to the decrease of the effect from the elastic collision. Hence, the
values of antenna gain strongly affected by size and mass of atom which subsequently
will give effect to the impact of collision itself. The decrease of elastic collision will
reduce the electron mobility which consequently effect to the level of conductivity
where the antenna gain is depend on [75].
Tables 4.5, 4.6 and 4.7 portray the summary of simulated results for different
gases at pressure 0.5 Torr, 5 Torr and 15 Torr respectively.
(a)
(b)
99
(c)
Figure 4.16: The effect of radiation pattern in polar plot for different gas at (a) 0.5 Torr (b) 5
Torr and (c) 15 Torr.
Table 4.5:
The performance of monopole plasma antenna for different gases at pressure 0.5 Torr.
Type of
Gases
Reflection
coefficient,
S11
(dB)
VSWR Electron
Density
(m-3
)
Collision
Frequency
(1/s)
Plasma
Conductivity
(S/m)
Gain
(dBi)
Directivity
(dBi)
Ar -26.43 1.10 8.12 1017
1.59 109 14.99 4.638 5.419
Ne -25.32 1.11 4.04 1017
6.87 108 16.59 4.803 5.502
Hg-Ar -29.04 1.07 1.13 1018
2.35 109 13.57 3.075 3.110
Table 4.6:
The performance of monopole plasma antenna for different gases at pressure 5 Torr
Type of
Gases
Reflection
coefficient,
S11
(dB)
VSWR Electron
Density
(m-3
)
Collision
Frequency
(1/s)
Plasma
Conductivity
(S/m)
Gain
(dBi)
Directivity
(dBi)
Ar -28.15 1.08 7.54 1018
2.113 1010
10.07 4.604 5.452
Ne -27.41 1.09 4.30 1018
1.10 1010
11.02 4.717 5.509
Hg-Ar -31.19 1.06 7.92 1018
2.33 1010
9.58 2.662 2.722
100
Table 4.7:
The performance of monopole plasma antenna for different gases at pressure 15 Torr
Type of
Gases
Reflection
coefficient,
S11
(dB)
VSWR Electron
Density
(m-3
)
Collision
Frequency
(1/s)
Plasma
Conductivity
(S/m)
Gain
(dBi)
Directivity
(dBi)
Ar -32.25 1.05 1.23x1019
6.338x1010
5.48 4.458 5.486
Ne -32.34 1.05 9.96x1018
3.474x1010
8.10 4.550 5.544
Hg-Ar -37.20 1.03 1.61x1019
9.28x1010
4.89 2.171 2.718
4.5 RESULTS AND DISCUSSION
To provide a better analysis, the measured return loss and radiation pattern for
the three types of cylindrical monopole plasma antenna are presented. The Rhode and
Schwarz Vector Network Analyzer ZVB20 were used to measure the reflection
coefficient, S11. To start the measurement, the equipments needs to be calibrated first,
systematic error from the measurement can be removed. On top of that, the antenna
reflection coefficient, S11 was measured at the anechoic chamber. The comparison
results between simulation and measurement for argon gas, neon gas and Hg-Ar (can
be found inside commercial fluorescent lamp) are presented in this section. For two
gases; argon and neon the comparison between simulation and measurement at 0.5
Torr was chosen because based on the analysis from the simulation result, 0.5 Torr
was the optimum pressure value which offered higher gain. Pressure use in Hg-Ar gas
is 0.6. Torr; which is the pressure refers to commercial product in market. Therefore
comparison pressure between simulation and measurement is 0.5 Torr (for argon and
neon gases) while for Hg-Ar gas is 0.6 Torr therein presented in this section.
101
(a)
(b)
(c)
Figure 4.17: Simulated and measured reflection coefficient, S11 of cylindrical monopole
plasma antenna. (a) Argon gas at 0.5 Torr. (b) Neon gas at 0.5 Torr. (c) Hg-Ar gas at 0.6
Torr.
102
Figure 4.17 exhibits the comparison between simulation and measurement
results for reflection coefficient, S11. The reflection coefficient, S11 for Argon gas is
measured at a frequency of 4.5 GHz with -18.03 dB and -26.43 dB at a frequency of
4.6 GHz during simulation. Meanwhile for Neon gas the reflection coefficient, S11 for
measurement is -21.61 dB at frequency 4.7 GHz and during simulation the reflection
coefficient, S11 at frequency 4.6 GHz is -25.32 dB. Meanwhile, the reflection
coefficient, S11 for Hg-Ar gas at frequency 4.74 GHz is -34.01 dB during simulation
and -35.71 dB at frequency 4.8 GHz during measurement. On the other hand, for
reflection coefficient, S11 a small frequency shift that occurred between the
measurement and the simulation is presumably due to the effect of flow of conduction
current through the plasma element and will give effect to the plasma formation.
However, in general, a good agreement has been achieved.
Figure 4.18 (a) and (b) exhibits the comparison between simulation and
measurement results for radiation pattern in polar plot for Argon and Neon gases
when the cylindrical monopole plasma antenna is at a frequency of 4.6 GHz in E-
Plane (phi=90°) and H-Plane (phi=0°) while Figure 4.18 (c) shows the comparison
results between simulation and measurement for Hg-Ar gas tube at a frequency of 4.5
GHz in E-plane and H-Plane. The results show that the radiation patterns of
cylindrical monopole plasma antenna in H-plane direction (at phi=0o) does not give
significant effect in radiation pattern, thus the radiation patterns is obvious and can be
observed in E-plane direction (at phi=90º).
Nevertheless, the radiation pattern does not display the expected Omni-
directional shape and it might be due to the fact that when the electromagnetic wave
arrived at the plasma region, the interaction between electromagnetic wave and
plasma will changes the surface current distribution of plasma antenna, as it is known
that the radiation pattern is determined by the surface current distribution of antenna.
Thus, the shape for far-field radiation pattern of plasma antenna will be changed.
However, good agreement between simulation and measurement has been achieved.
103
(a)
(b)
(c)
Figure 4.18: Simulated and measured radiation patterns. (a) At frequency 4.6 GHz Argon gas
in H-plane (left) and in E-plane (right). (b) At frequency 4.6 GHz Neon gas in H-plane (left)
and in E-plane (right). (c) At frequency 4.5 GHz for Hg-Ar gas in H-plane (left) and in E-
plane (right).
104
4.6 SUMMARY
In this chapter, cylindrical monopole plasma antenna using argon gas, neon gas
and Hg-Ar gas which consists of pressures 0.5 Torr, 5 Torr and 15 Torr have been
described comprehensively. This chapter also includes a comparative analysis on the
effects of several antenna parameters from the difference pressures and difference
gases.
From the analysis, it can be concluded that, when the pressure is increased, the
electron density, ne also increases. From [76], the pressure of gas is directly
proportional to the electron density, ne .Besides, the collision frequency, νc also is
pressure dependent, high pressures will increase the collision frequency, νc [62]. As a
result, the reflection coefficient, S11 will deeper while the gain is decrease. Based on
equation 3.38, when the value of collision frequency, νc increase, the plasma
conductivity, σ value will decrease. Consequently, this will influence the gain of
antenna and the radiation pattern will change too. Thus from the analysis it can be
concluded that the electron density, ne and collision frequency, νc can influence the
performance of antenna. In addition, the value of antenna gains also affected by size
and mass of atom. When the size and mass of atom is increases, the gain will
decrease.
The results from measurements seem to agree well with the simulation results.
Based on the measurement and analysis results, it can be concluded that, the
cylindrical monopole plasma antenna with argon gas, neon gas and Hg-Ar gas
(contained inside fluorescent tube) can be used to radiate radio signals. However the
typical homemade plasma which only consist argon gas and neon gas required more
complicated experimental apparatus, and therefore, it increased the complexity and the
cost of realizing plasma antenna. Thus to design low cost plasma antenna and
commercially available market plasma source, the fluorescent tube is a suitable option
compared than neon and argon lamp. Therefore, in the next chapter, discussion will be
focusing more on the design of plasma antenna as wireless transmission by using
commercial fluorescent tube at 2.4 GHz frequency. Even though, based on analysis in
this chapter, the frequency at 4.6 GHz will be used to design an antenna due to
unavailability of material and limitation of technology to produce discharge tube with
105
2.4 GHz frequency. According to literature review [2-3], [38], [77], 4.6 GHz
frequency will produce the same concepts analysis as same as 2.4 GHz frequency.
106
CHAPTER FIVE
DEVELOPMENT OF MONOPOLE PLASMA ANTENNA USING
FLUORESCENT TUBE FOR WIRELESS TRANSMISSION
5.1 INTRODUCTION
Plasma antenna is a general term that represents the use of ionized gas as a
conducting medium instead of a metal to either transmit or reflect a signal to achieve
radar [76-77], or stealth or communication purpose [59]. There are many ways to
generate plasma medium as a conductor element such as UV laser irradiation, or by
laser initiated pre-ionization or by simply using commercial fluorescent lamp as a
plasma antenna. In this work the commercial fluorescent lamp was chosen because it
was low cost to produce plasma element. Besides that, by choosing fluorescent lamp
as an plasma antenna, the complexity in building a homemade plasma tube as
presented in [25], [80], [5], [81] ,[27] and [57] can be avoided. The typical homemade
plasma tube provides more flexibility to change the plasma parameters by controlling
the excitation power, type of encapsulated gas, pressure of gas, and also the density of
the gas. However this method required more complicated experimental apparatus, and
therefore, it increased the complexity and the cost of realizing plasma antenna.
This chapter presents the investigation pertaining to monopole plasma antenna
by using a commercial fluorescent tube and reviews the antenna performance as a
transmitter and a receiver. As a comparison to the plasma antenna proposed in the
literature review previously, the plasma antenna in this study was made from
cylindrical shaped fluorescent lamp that functioned as a radiating element with target
frequency at 2.4 GHz for Wi-Fi application. In this research work, 6500 K for color
temperature, with 18 W was used as a plasma source. The commercial fluorescent
lamp consisted of argon gas and mercury vapor with a diameter of 28 mm and a length
589.8 mm. The brief introduction concerning the technology of fluorescent lamp is
described in section 5.2. The parametric study and the effect the parameters to the
antenna were studied and the results were compared. This part is presented in section
5.3. In section 5.4, the comparative results between metal antenna and plasma antenna
107
were investigated. Besides, the simulation and the measurement results are presented
in section 5.5 to demonstrate the excellent performance of this antenna. Furthermore,
in order to show that monopole plasma antenna with fluorescent lamp can react as a
metal antenna, the experiment of radiation signal have been done in the Antenna
Research Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA. The
results are presented in section 5.6.
5.2 MERCURY-ARGON (Hg-Ar) FLUORESCENT LAMP
Most of the discharge lamps in use at the present time are the mercury-argon
fluorescent lamps. A fluorescent lamp is a low-pressure mercury electric discharge
lamp. It was discovered by a French physicist, Alexandre E. Becquerel in 1857, who
investigated the phenomena of fluorescence and phosphorescence, as well as theorized
the development of fluorescent tubes similar to those made today. Alexandre
Becquerel experimented with coating electric discharge tubes with luminescent
materials, a process that was further developed in later fluorescent lamps [82]. Some
of the advantages of using fluorescent lamp are that their high performance in
converting electrical power to light, size flexibility, and good color rendering
properties that make them the most successful lamp product. Light is mainly produced
by conversion of short wavelength UV radiation to visible radiation with the phosphor
coating on the inner wall of the tube [83].
A typical hot cathode fluorescent lamp consists of a glass tube with its inner
surface coated with fluorescent powder. It is filled with argon gas, a drop of mercury,
and the filaments are tungsten wire electrodes coated with a thermionic emitter sealed
into each end of the tube [84]. The rare gas argon is added to the lamp primarily to
assist starting since the vapor pressure of mercury is very low initially. When current
flows through the ionized gas between the electrodes, it emits ultraviolet (UV)
radiation from the mercury arc. The UV radiation is converted to visible light by a
fluorescent coating on the inside of the tube. The lamp is connected to the power
source through ballast, which provides the necessary starting voltage and operating
current. Figure 5.1 shows the construction of a fluorescent lamp.
108
Figure 5.1: Construction of the Fluorescent Lamp [85].
5.3 PARAMETRIC STUDY ON A MONOPOLE PLASMA ANTENNA USING
FLUORESCENT TUBE
An inclusive parametric study on a monopole plasma antenna using
fluorescent tube was conducted to identify the effects of various dimensional
parameters, particularly in changing the dimensions of structure antenna.
As initial requirements for monopole plasma antenna using fluorescent tube,
the design was based on an operating frequency of 2.4 GHz. The dielectric tubes used
in the simulation were made from lossy glass borosilicate (Pyrex) with permittivity at
4.82 and the thickness of the glass was 1 mm. The plasma was defined by using the
Drude model (CST software) as mentioned in chapter 3. The schematic diagram of a
monopole plasma antenna is shown in Figure 5.2.
109
Figure 5.2: The structure of a monopole plasma antenna.
Figure 5.2 shows the structure of a monopole plasma antenna using
commercially available fluorescent tube which is the glass is from borosilicate
(Pyrex) with permittivity at 4.82 with 589.8 mm in length (LFT) and diameter 28
mm (DFT). The gas filled inside the fluorescent tube was argon gas and a drop of
mercury vapor. The gas argon was added to the fluorescent tube to assist in
starting since the vapor pressure of mercury is very low initially.
Before the radiation began, the signals were connected to the tube with a
coupler. This is called coupling sleeve. When the RF signals were applied to the
coupling sleeve, the RF current flowed in the coil and generated an RF electric
field. In addition, at the same time when the voltage was applied to the monopole
plasma antenna, an electric field was produced and this electric field caused the
current to flow in the plasma medium. The combination of current oscillated on
the surface of the metal and this was caused by the disturbing currents in the
interface between plasma and coupling sleeve. On top of that, these two electric
fields were emitted from the monopole plasma antenna and propagated through
the space [51-82] . Nonetheless, in this work, the coupling sleeve with a width WA
of 18 mm was mounted 12 mm below at the lower end of the fluorescent tube. The
coupling sleeve consisted of aluminum tape and copper wire. The copper wire was
wrapped tightly at the aluminum tape. In this research work, the number of turns at
the coupling sleeve had been 5. The function of coupling sleeve was to couple the
110
RF and the plasma element inside the fluorescent tube. The RF current from the
network analyzer flowed in the coupling sleeve and generated an RF electric field
to be coupled with the plasma column inside the discharge tube. Besides, the SMA
connector was applied to maintain the 50 Ohms impedance for the RF generator.
The power to energize the fluorescent tube was supplied by a set of electronic
ballast with specification of 220-240V, 50-60Hz. The electronic ballast was
chosen compared to magnetic ballast because electronic ballast is lighter in weight
than magnetic ballast and it is more efficient compared to magnetic ballast [87].
Moreover, the length of plasma, diameter of plasma, number of turn of copper
coil, diameter of copper wire, distance between coupling sleeve and SMA
connector, and position coupling sleeve at the fluorescent tubes were optimized to
obtain the best results. Besides, the effect of width of aluminum tape was also
investigated for antenna performance. The parameters and dimension of the
monopole plasma antenna are tabulated in Table 5.1. The comparative results of
the proposed antenna performance are described and further discussed in terms of
reflection coefficient, gain, VSWR, and radiation patterns.
Table5.1:
Parameters and dimension of monopole plasma antenna
Parameter Label Dimension(mm)
Length of monopole plasma antenna LFT 589.8
Diameter of monopole plasma antenna DFT 28
Thickness glass t 1
Length of aluminum tape LA 30
Position Coupling Sleeve at the monopole plasma antenna LB 22
Distance from SMA connector to coupling sleeve LC 9
Width of aluminum tape WA 18
No of turns N 5
Diameter copper coil DC 0.25
111
5.3.1 Effects of the Length of Monopole Plasma Antenna.
Figure 5.3 shows the reflection coefficient, S11 results for simulated when
optimized length plasma column from 504.8 mm ≤ LFT≤ 629.8 mm with
increment 40.0 mm. From simulation results clearly shows that when increase the
length of plasma antenna the resonant frequency will shifted to the high
frequency. However, when increase the length of plasma antenna, the plasma
frequency also changes. Thus it will affect the resonant frequency of the antenna.
This behavior indicates that the resonant frequency of plasma antenna can be
achieved by controlling the plasma frequency. Hence, this analysis proved that,
the length of monopole plasma antenna has a greater influence on the operating
frequency.
Figure 5.3: The effects on reflection coefficient, S11 due to change of length monopole
plasma antenna.
2.4GHz = -43.29dB
112
5.3.2 Effects of Diameter Plasma Antenna
The effect of the diameter on fluorescent tube has been analyzed to
observe which value gives the better result. The diameter of plasma antenna are
varies from 20 mm until 36 mm with an increment of 4 mm. From Figure 5.4
shows that, the reflection coefficients, S11 fluctuated when the diameter of the
plasma column was varied. It was because; when the diameter of plasma antenna
was changed, the electron density of plasma changed as well. Thus, it influenced
the performance of the antenna. From the observation, the best result providing
good impedance at 2.4 GHz was obtained when the diameter was 28 mm with s-
parameter was equal to -43.29 dB. Hence, 28mm was chosen for the final design.
Figure 5.4: The effects on reflection coefficient, S11 due to change of the diameter of
plasma antenna.
5.3.3 Effects of Parameter for coupling sleeve.
In contrast to conventional metallic antennas, it is impossible to make a
direct electrical contact with the plasma conductor because the plasma is
encapsulated in a dielectric tube. For that reason, it was necessary to use
capacitive coupling to launch surface waves as a way to radiate radio signals. As
mentioned in section 5.3, the plasma antenna needed a coupler to transmit and to
receive signals. Only a small portion of monopole plasma antenna was covered
with coupling sleeve. The structure of coupling sleeve as shown in Figure 5.5.
2.4GHz = -43.29 dB
113
Figure 5.5: Coupling sleeve structure.
To design coupling sleeve, some parameters such as the width of aluminum,
the position of coupling sleeve to the plasma antenna, the diameter of coil, the
number of turns in coupling sleeve, the distance between SMA connector to the
coupling sleeve, were taken into consideration.
(a) (b)
(c) (d)
2.4GHz = -43.29dB
2.4GHz = -43.29dB
2.4GHz = -43.29dB
2.4GHz = -43.29dB
114
(e)
Figure 5.6: Effects on reflection coefficient of parameter for coupling sleeve. (a) Numbers
of turns. (b) Width of aluminum tape. (c) Position of coupling sleeve. (d) Diameter of coil.
(e) Distance between SMA connector to coupling sleeve.
The numbers of turns of the coupling sleeve have been optimized to identify if
it affected the performance of the antenna. However, from this analysis, the
number of turns in coupling sleeve give minimum effect to the reflection
coefficient as illustrates in Figure 5.6 (a). In this analysis, the number of turns
were varies from 3 to 8 turns.
Figure 5.5(b) depicts the simulated results with varied width of aluminum
tape. WA was simulated in four, which varied from 16 mm to 22 mm with 2 mm
of increments. From Figure 5.5 (b), it was found that when the width of aluminum
tapes increase, the S11 slightly shifted to the left. From this analysis, the optimum
reflection coefficient at operating frequency of 2.4 GHz when the aluminum tape
equal to 18mm (-43.29 dB).
Another parameter that had to be analyzed was the position of coupling sleeve
to the monopole plasma antenna; LB. Figure 5.5(c) exhibits the simulated result
for reflection coefficient when the distance from the bottom of the monopole
plasma antenna to the coupling sleeve is varied from 2 mm≤LB≤ 290 mm.
Besides, from Figure 5.5 (c) depicts that, when increase the position of coupling
sleeve the operating frequency shifted to the upward. In addition, the best result
providing a good impedance matching at 2.8 GHz is obtained when LB is 22 mm
with S11 at -43.29 dB. Hence, this position of coupling sleeve was chosen for the
final design
Meanwhile, Figure 5.5(d) shows the comparison results of different copper
coil diameters, DC for coupling sleeve from 0.1 mm until 1.3 mm with an
increment of 0.4 mm. From the simulation results, it is observed that the
2.4GHz = -43.29dB
115
reflection coefficient results are slightly shifted to the downward when the
diameter of copper coil increases. The diameter coil of 0.5 mm give the best result
at an operating frequency of 2.4GHz (-43.29dB). Thus, the final design for copper
coil is 0.5 mm.
Another parameter that affected the targeted operating frequency is the
distance between coupling sleeve to the SMA connector, LC as shown in Figure
5.5 (e). The effect in s-parameter, S11 is observed when LC is varied from 7 mm to
11 mm with an increment of 1 mm. Moreover, the results from the analysis
showed that the operating frequency shifted to a lower frequency. Hence, the
function of LC as a transmission line that connected the plasma medium to the RF
signal and carried the electromagnetic wave which was needed to minimize
reflections and power loss. Thus, the increase in LC caused more losses in plasma
antenna and signal reflection. From this analysis, the optimum result at a
frequency of 2.3 GHz with s-parameter is -47.76 dB. However, the targeted
operating frequency in this research is 2.4 GHz, so that the appropriate LC is equal
to 9mm with reflection coefficient, S11 = -43.29 dB. In general, from this analysis,
the parameter of coupling sleeve doesn’t to influence the performance of antenna
in terms of operating frequency.
5.4 ANALYSIS BETWEEN MONOPOLE PLASMA ANTENNA AND
METAL ANTENNA
As mentioned in chapter 2, the plasma element can transmit and receive radio
frequency same as metal element such as copper wire and copper rode when the
plasma frequency is much greater than operating frequency [84-85]. Thus, in this
part, the comparison of antenna performances between monopole plasma antenna
and metal antenna is presented. Metal antenna was designed to be identical to the
monopole plasma antenna. Besides, it is very essential to observe the condition of
monopole plasma antenna during ON and OFF condition.
116
Figure 5.7: Comparison of simulation results of reflection coefficient,S11 between metal
antenna, condition during plasma OFF and ON.
Three condition of antenna were simulated; monopole plasma antenna (plasma
ON), metal monopole antenna and the condition when plasma OFF. Figure 5.7 shows
the comparison results between monopole plasma antenna by using fluorescent lamp
during condition plasma antenna ON, plasma antenna OFF and metal monopole
antenna. As depicted in Figure 5.7 the reflection coefficient, S11 of monopole plasma
antenna during ON state at frequency 2.4 GHz is -43.29 dB while for OFF state at 2.4
GHz is -8.10 dB. For metal antenna are -21.65 dB at operating frequency of 2.46 GHz.
From this analysis, when monopole plasma antenna in OFF state, the reflection
coefficient, S11 is more than -10 dB ( -8.10 dB) while when monopole plasma antenna
in ON state the reflection coefficient, S11 is less than -10 dB at frequency 2.4 GHz
which is show good impedance matching. Thus it proof that during plasma ON it can
become as conductor element like a metal antenna while during OFF condition it
become as a dielectric.
Figure 5.8: VSWR for plasma antenna on, off and metal antenna.
117
Figure 5.8 shows the voltage standing wave ratio (VSWR) against frequency
(GHz) during plasma ON, plasma OFF and metal antenna monopole results. From the
simulation the value of VSWR during plasma ON state is 1.01 and for metal antenna
is 1.18 at frequency 2.4 GHz while during plasma OFF state is 2.29. From this
comparison shown that, the plasma antenna during ON state have a perfectly matched
to the antenna’s impedance same with conventional metal antenna. However during
plasma OFF, the value of VSWR is greater than 2. The antenna can be described as
having a good match when have a VSWR value under 2 and was considered as
suitable for most antenna applications. Thus, when plasma OFF, the antenna behaves
as a dielectric.
Figure 5.9 : Simulated radiation patterns of plasma monopole antenna during ON and metal
antenna in polar plots in the E-plane (phi = 90°).
Figure 5.9 displays the radiation pattern E-plane (phi=90°) for plasma antenna
during ON state and metal antennas. It is obvious that, the radiation patterns when
plasma antenna ON was quite similar to the metal antenna. The gain of plasma
antenna is 3.953 dBi and metal antenna is 5.140 dBi. The gain of plasma antenna
during ON is lower compare than metal antenna due to the much lower conductivity
of the plasma compared with the metal antenna.
5.5 SIMULATION AND MEASUREMENT RESULTS
Figure 5.10 exhibits the comparison between simulation and measurement
results of reflection coefficient, S11 for the monopole plasma antenna using fluorescent
tube. The measured results indicated that the antenna was capable in operating at 2.4
GHz. The simulated result during plasma ON is -43.29 dB at frequency 2.4 GHz while
118
for measured result the reflection coefficient, S11 at 2.4 GHz is -22.10 dB. Result
measurement for reflection coefficient, S11 during plasma OFF at frequency 2.4 GHz
is -8.42 dB. This is shown that, during plasma OFF there is no conductor element and
as a result cannot performance as an antenna.
From Figure 5.10, the measured result seems to have lower value of S11 than
simulated result at frequency 2.4 GHz is presumably due to the parasitic effect from
imperfect solder between SMA connector and coupling sleeve. Besides, the difference
between simulation and measurement might be due to the current flow to fluorescent
tube that might not be consistent and affected the condition of plasma produced in the
real experiment. However, in general, a good agreement has been achieved between
simulation and measurement.
Figure 5.10: Simulated and measured reflection coefficient, S11 for monopole plasma antenna.
Apart from that, the radiation patterns of monopole plasma antennas during
ON were observed in both simulated and measured scenarios. The measured and
simulated radiation patterns at E-plane (phi=90°) for the monopole plasma antenna
excited at 2.4 GHz are shown in Figure 5.11. The results show that the radiation
patterns of cylindrical monopole plasma antenna in H-plane direction (at phi=0o) does
not give significant effect in radiation pattern, thus the radiation patterns is obvious
and can be observed in E-plane direction (at phi=90º).
Good agreement and well behaved radiation patterns were obtained. This was
attributed to the omni-directional characteristics of monopole plasma antenna. In
comparison, the measured scenarios displayed some distortions in terms of radiation
119
pattern which were due to losses and connectivity impurities. Besides, the cross-polar
radiation pattern is lower than -10 dBi.
(a) (b)
Figure 5.11: Simulated and measured radiation patterns of monopole plasma antenna (ON) at
2.4 GHz in (a) H-Plane and (b) E-Plane.
5.6 WIRELESS SIGNAL TRANSMISSION EXPERIMENT
In this section, the experiment radiation signal is presented. To prove that
monopole plasma antenna with fluorescent tube is working, the experiment radiation
signal were conducted. For the first experiment, the main objective is to prove that the
received signal is come from plasma antenna not from coupling sleeve. After that, the
second experiment is to show that plasma monopole antenna can served as a
transmitter and the third experiment as a receiver. The experiments concerning signal
strength for plasma monopole antenna are also presented in this section.
5.6.1 Experiment Radiation Signal
The aim of this experiment was to determine that the source of signal
generated is transmitted from plasma antenna and not coupling sleeve. The signal that
is produced can be detected by using Wi-Fi analyzer software that can be easily
installed in smart phone. The Wi-Fi analyzer is software develops in which main
functions are to test and observe the signal strength of an antenna.
From this experiment, three conditions of plasma antenna were being tested to
show that generated and transmitted signal is come from plasma antenna and not from
coupling sleeve. In first condition, coupling sleeve was uncovered with aluminum-
wrapped shielding box and fluorescent tube was switched ON, the result shows that
strength of signal from plasma antenna is higher as compared other signals (red line
120
represent “Plasma Antenna UiTM S.Alam”). For second condition, the coupling
sleeve was covered with aluminum-wrapped shielding box and fluorescent tube lamp
was switched ON .The result shows signal generated from plasma antenna is the same
with first condition tested which is higher compared other signals. This proves that the
received signal was generated and transmitted from plasma antenna because even
though the coupling sleeve was covered with aluminum-wrapped shielding box, still
signal was traceable. For third condition, the coupling sleeve was again covered with
aluminum-wrapped shielding box and fluorescent tube was switched OFF. Result
from third condition shows that the signal strength transmitted to Wi-Fi analyzer has
dropped to low signal. Thus, from this experiment it is proven that the signal was
came from plasma antenna. Table 5.2 shows the summary results for three conditions.
Table 5.2:
Summary results signal strength for three conditions.
Condition Signal Strength Conclusion
1st : Coupling sleeve was not covered
with aluminum-wrapped shielding box
and fluorescent tube was switched ON.
Signal strength
good
2nd
: Coupling sleeve was covered with
aluminum-wrapped shielding box and
fluorescent tube was switched ON
Signal strength
good
121
3rd
: Coupling sleeve was covered with
aluminum shielding box and fluorescent
tube was switched OFF.
Signal strength
weak
5.6.2 Monopole Plasma Antenna as a Transmitter
In experiment 2, monopole plasma antenna with fluorescent tube was set to
serve as a transmitter. Besides, a spectrum analyzer was used to observe the received
frequency spectrum, to analyze if the plasma antenna worked properly as a
transmitter. The measured signal at the receiver is shown in Figure 5.12. The result
showed a peak signal at 2.4 GHz, which matched the transmitting signal from the RF
generator. The peak rose approximately 15 dB above the noise floor. The captured
signal frequency was within the operating frequency range of the constructed plasma
monopole antenna, which had been confirmed in the previous return loss measurement
experiment. This proved that this antenna could transmit information at that
frequency. Meanwhile, Figure 5.13 shows that there was no peak signal when the RF
generator was turned off. This indicated that the captured signal originated from the
RF generator in the experimental setup.
Figure 5.12: Captured signal when plasma antenna serves as transmitter.
122
Figure 5.13: Noise floor when the RF generator is turned off.
5.6.3 Monopole Plasma Antenna as a Receiver
Meanwhile, experiment 3 observed the functionality of the energized
fluorescent tube as a receiver. The signal transmitted from the reference antenna at the
transmitter was captured by the energized fluorescent tube, and was observed by the
spectrum analyzer. Figure 5.14 shows that the signal was captured at 2.4 GHz, which
matched the transmitting signal’s frequency of the RF generator. Similar to the
previous experiment, the peak rose more than 20 dB above the noise floor. Besides,
Figure 5.15 shows the result of signal received when the fluorescent tube was de-
energized and removed from the receiving system. In this case, no peak signal was
observed from the graph since the plasma antenna was de-activated and removed from
the system.
Figure 5.14: Captured signal when plasma antenna serves as receiver.
123
Figure 5.15: Noise floor when the plasma antenna was removed from the receiver system.
5.6.4 Signal Strength for Monopole Plasma Antenna
Figures 5.16 and 5.17 represent the signal strength results of Wi-Fi channel in
communication laboratory. These results were measured using Wi-Fi Analyzer
applications. From the results, red line refers to the result of plasma monopole
fluorescent tube antenna named ‘Plasma Antenna UiTM S.Alam’, while the blue and
the green lines represent other signal strength that come from other Wi-Fi channels in
the same room. Figure 5.16 shows the performance of signal strength when the AP
router was connected to the fluorescent tube antenna. It proved that the antenna
worked properly and possessed good signal strength, which was approximately 45
dBm. Meanwhile, Figure 5.17 shows the result of signal strength when the fluorescent
tube antenna was removed from the AP router. The signal dropped about 40 dB,
which means that the signal was not radiated and was very weak.
124
Figure 5.16: Performance of Signal Strength when the fluorescent tube antenna was
connected to the AP Router.
Figure 5.17: Performance of Signal Strength when fluorescent tube antenna disconnected
from AP Router.
5.7 SUMMARY
In this chapter, the simulation and the measurement results of plasma antenna
showed that a simple fluorescent tube, used for household applications, can be used to
work as a plasma antenna for Wi-Fi application. This could be done by implementing
the coupling technique by applying AC voltage 240 V across the electrodes of
fluorescent tube. In this research work, the plasma antenna was fabricated by using
commercial fluorescent tube with a length of 589.8 mm and a diameter of 28 mm, as
well as being measured at frequency 2.4 GHz.
125
Besides, the measurement showed that the radiation patterns of the plasma
antennas measured at frequency 2.4 GHz had been quite similar to the radiation
pattern of classic monopole metal antenna. Thus, the findings obtained from this
study indicated that the plasma antenna could be considered as a monopole antenna.
Besides, the plasma antenna prototype yielded reflection coefficient, S11 < -10 dB,
which was suitable for indoor wireless transmission applications. In addition, the
results from measurements of each structure seemed to agree well with the simulation
results.
Therefore, the commercial fluorescent lamp has the potential to be used as a
good conductor element and it is also a low-cost plasma antenna. Further research
with the application of commercial fluorescent lamp as a reflector element is
presented in the next chapter.
126
CHAPTER SIX
DEVELOPMENT OF RECONFIGURABLE PLASMA ANTENNA
ARRAY
6.1 INTRODUCTION
Reconfigurable antennas have attractive a number of features, such as the
ability to reconfigure themselves autonomously to adapt to the changes or with the
system to perform entirely different functions. The reconfigurable antenna is also
capable of providing a single antenna for use with multiple systems. Mostly, in
reconfigurable antennas, the antennas are constructed by using metallic elements,
along with active devices. These active devices are employed to provide switching
mechanism for the antennas to steer beam in particular directions. However, this
chapter discusses and explains the plasma medium as reconfigurable antennas instead
of using metallic antenna.
As mentioned earlier, plasma elements have a number of potential advantages
over conventional metal elements for antenna design as they permit electrical, rather
than physical control as their characteristics. Moreover, antenna arrays can be rapidly
reconfigured without suffering perturbation from unused plasma elements. Thus, it
can offer extra advantage to reconfigure antenna compared to metallic antenna
without using active devices.
In this chapter, the behaviors of the reconfigurable plasma antenna array were
studied and applied to the design of a new antenna.
6.2 RECONFIGURABLE PLASMA ANTENNA ARRAY
A new structure of a reconfigurable plasma antenna array was constructed by
using commercial fluorescent lamp at an operating frequency of 2.4 GHz. The
fluorescent tube functioned as a plasma element and the reason for selecting a
commercial fluorescent lamp as plasma element has been discussed in the previous
chapter. Likewise, the development of the plasma antenna with fluorescent lamp has
127
been proved and explained in previous discussion. It has also been demonstrated
previously that fluorescent lamp can be used as a radiating element. This shows that
fluorescent lamp has the ability to function like a metal element and at the same time,
it can behave like a reflector element.
In contrast to conventional antennas that produce fixed directional radiation
patterns, the reconfigurable plasma antenna array studied here had been capable of
steering the beam pattern over 360° of freedom. The main objective of this work was
to design, to analyze, and to develop a reconfigurable antenna by using plasma
element with the capabilities of beam scanning and beam shaping. The characteristics
of the antenna radiation were simulated using the CST Microwave Studio. Both
simulation and measurement results are discussed in this section.
6.2.1 Reconfigurable Plasma Antenna Array Structure
To simulate the performance of an antenna design, CST MWS software was
used. The structure of the proposed antenna is shown in Figure 6.1(a), (b), and (c).
The reconfigurable plasma antenna array structure consisted of 12 tubes of
commercial cylindrical shaped fluorescent tubes that contained the mixture of mercury
vapor and argon gas. The ground was circular aluminum with a thickness of 3 mm and
radius of 105 mm. The height of each plasma tube from the ground plane surface, LPA
is 288 mm and its diameter is 16 mm. Meanwhile, the energy source was supplied by
a monopole antenna that resonated at 2.4 GHz located at the center of the ground
plane. Besides, the height of the monopole antenna is 35 mm with a diameter of 3
mm. Moreover, the antenna was fed by a standard SMA connector that was located in
the middle of the ground. The probe feed (coaxial feed) is a technique that was used in
this project for feeding microstrip patch antennas, fed by a SMA connector. The SMA
connector was designed based on the specification by using Teflon with dielectric
constant = 2.08. The impedance of feeding coaxial transmission line is 50 Ω. The
tubes used in the simulation were made from lossy glass borosilicate (Pyrex) with a
permittivity = 4.82. Meanwhile, the tube wall (glass) has a thickness, t = 0.1 mm. The
distance between the monopole antenna and the fluorescent tubes, DBB is equal to 75
mm, whereas the angle between the centers of the two adjacent elements is 30º. The
128
parameter and dimension of reconfigurable plasma antenna array is presented in Table
6.1.
(a) (b)
(c)
Figure 6.1: Geometry of the reconfigurable plasma antenna array. (a) Top view. (b) Side
view. (c) Overall structure.
x
z
y
129
Table 6.1:
Parameters and dimension of reconfigurable plasma antenna array. Parameter Label Dimension(mm)
Space gap between plasma elements DAA 36
Distance between plasma element to monopole
antenna
DBB 70
Aluminum ground plane radius DCC 105
Aluminum ground plane thickness t 3
Length of plasma element LPA 288
Diameter of plasma element DPA 16
Length of monopole antenna LM 35
Diameter of monopole antenna DM 3
Angle between two adjacent plasma elements θ 30°
6.3 ANALYSIS OF RECONFIGURABLE PLASMA ANTENNA ARRAY
In this section, the effects of distance between monopole antenna and
fluorescent tubes, DBB towards radiation patterns of reconfigurable plasma antenna
array had been investigated. The results of return loss were also presented to ensure
that the effects took place at the desired frequency mode. Besides, the target frequency
band was 2.4 GHz.
6.3.1 Effects of Distance between Monopole Antenna to Fluorescent Tube, DBB
Figure 6.2 shows simulation result of reflection coefficient, S11 on the effect of
different distances between monopole antenna to fluorescent tube, DEE. The distance
between monopole antenna and fluorescent tube had been varied from 50 mm until 80
mm with an increment of 10 mm. As depicted in Figure 6.2, it clearly shows that the
distance between monopole antenna to fluorescent tube, DBB has significant effects on
return loss and resonant frequency. The best result for the antenna to operate at a
frequency of 2.4 GHz is when DEE = 70 mm.
130
Figure 6.2 : The effect of distance between monopole antenna to fluorescent tube.
In this analysis, the peak gain is an important element that contributes to the
good performance of reconfigurable plasma antenna array. Figure 6.3 shows the
comparison of simulated gains when the DEE is varies at operating frequency of 2.4
GHz. The gain value is referred as theta gain, at theta =50o. Highest gain is achieved
when the value of DEE value is 70 mm.
Figure 6.3 Comparison of simulated gains at frequency 2.4 GHz in H-Plane.
131
(a) (b)
Figure 6.4: Comparison of radiation patterns in polar-plot in (a) E-plane and (b) H-plane.
Figure 6.4 shows the simulation results of radiation patterns with respect to
different distances between monopole antenna to fluorescent tube, DEE at frequency
2.4 GHz in E-plane and H-plane at ϕ=50°. The results show that the radiation patterns
of reconfigurable plasma antenna array in H-plane direction (at ϕ= 50o) give more
significant effect in radiation pattern compared the radiation patterns in E-plane
direction. As clearly shown in Figure 6.4, when DEE is 80 mm the beam is more focus
and this lead to high directivity. However the back lobe of DEE is higher as compared
when DEE is 50 mm, 60 mm and 70 mm respectively. The results also indicate that the
back lobes of DEE = 50 mm and DEE = 60 mm are smaller than 70 mm but having
lower gain comparing to DEE = 70 mm. Thus the best optimize for distance between
monopole antenna to fluorescent tube, DBB is 70 mm.
6.3.2 Effects of Thickness of Ground, t.
As depicted in Figure 6.1, the structure of reconfigurable plasma antenna array
consisted of ground aluminum. A parametric analysis was conducted to attain the
optimum performance of antenna. In this parametric analysis, the effect on S11 has
been investigated at frequency 2.4 GHz. The thickness ground, t was varied from 2
mm to 5 mm by a constant increment of 1 mm. Figure 6.5 illustrates the effects in S11
when t is varied. The optimum result for S11 is when t is equal to 3 mm.
132
Figure 6.5: Effect on S11 when t is varied.
6.3.3 Effect of Length of Monopole Antenna. LM.
Figure 6.6: Effect on reflection coefficient, S11 and resonant frequency when LM is varied.
In this case, the effect of length of monopole antenna, LM on return loss and
resonant frequency were investigated. The design of the antenna is illustrated in
Figure 6.1(c). As depicted in Figure 6.6, it clearly shows that the length of monopole
antenna, LM has significant effect on return loss and resonant frequency. From the
result in Figure 6.6, LM = 35 mm is chosen so that the antenna is expected to operate at
a frequency of 2.4 GHz.
133
6.3.4 Effects of the Numbers of Fluorescent Tubes and Adjacent Angle, θ.
In this section, the effect of the numbers of fluorescent tubes and adjacent
angle, θ has been investigated. Changing the numbers of fluorescent tubes will also
change the adjacent angle between the two plasma elements, θ. Figure 6.7 explains the
relationship between the number of fluorescent tubes and adjacent angle.
(a) (b) (c)
Figure 6.7: Relationship between the number of fluorescent tubes and adjacent angle.
(a) 10 fluorescent tubes were used with only 6 elements activated (b) 12 fluorescent tubes
were used with only 7 elements activated (c) 20 fluorescent tubes were used with only 15
elements activated.
In Figure 6.7 shows the different number of fluorescent tubes are use as
compared in figure (a),(b) and (c).Figure 6.7(a) will give greater adjacent angle (θ
=36°) than figure 6.7(b) = (θ=30°) and 6.7(c) = (θ= 18°). Hence, when increase the
number of fluorescent tubes, the angle between the two adjacent fluorescent tubes will
decrease.
(a) (b)
Figure 6.8 : Simulated radiation pattern in polar plot in (a) E-Plane and (b) H-plane.
134
Figure 6.8 exhibits the simulated co-polarization of reconfigurable plasma
antenna array in polar plot E-plane and H-plane at frequency 2.4 GHz. The plots were
based on the radiation patterns which were cut based on E-plane and H-plane. The
reason why cut in H-plane because it give more significent effect and can observe
maximum gain at H-plane compared the radiation patterns in E-plane direction. Figure
6.9 illustrates the changes in s-parameter, S11 when the number of elements and the
adjacent angle, θ were varied. Based on this analysis, the best number of elements and
adjacent angle, θ so that the reconfigurable plasma antenna array can be operate at
frequency 2.4 GHz is when θ is 30° and the number of elements is 12. Meaning that,
number of deactivated elements (switched OFF) is 5. On top of that, Table 6.2 shows
the summary of the performances concerning the analysis of the number of element
and the angle between the two adjacent elements. In the performance analysis based
on table 6.2, the deactivation of elements was made different in each sequence.
Reason behind this decision is to get a sequence that can produce a symmetrical main
lobe radiation pattern.
Figure 6.9: Simulation reflection coefficient, S11.
Table 6.2
The performances analysis of the number of element and the angle between two adjacent
elements.
Number of
elements
No of
deactivated
elements
(switched
OFF)
Angle
between two
adjacent
elements, θ
HPBW(°) Side
lobe
level
(dB)
Gain (dB) Reflection
coefficient,
S11 at 2.4
GHz (dB)
9 2 40° 72.3 -16.1 12.49 -20.34
135
12 5 30° 64.1 -24.3 13.04 -29.05
15 5 24° 65.8 -33.4 13.03 -21.34
18 6 20° 65.9 -29.7 12.89 -18.82
20 5 18° 77.3 -19.8 11.94 -20.51
6.3.5 Effects of Fluorescent Tubes on Radiation Pattern
In order to observe the effects of fluorescent tubes on radiation pattern, the
design model has been simulated and measured by two conditions;
i) Monopole antenna without fluorescent tubes, and
ii) Monopole antenna surrounded by fluorescent tubes (plasma OFF)
(a)
(b)
Figure 6.10: Simulation and measurement results for radiation pattern in H-plane (right) and
E-plane (left). (a) Plasma off. (b) Monopole antenna only.
As depicted in Figure 6.10, simulated radiation patterns in polar plots are
compared with the measurement results in H-plane and E-plane for two conditions.
136
The radiation pattern in H-plane give more significent effect and can observe
maximum gain at H-plane compared the radiation patterns in E-plane direction. The
results shows for both conditions are quite similar radiation pattern in polar plot.
Hence, both simulated and measured results can be considered as to have good
agreement.
The gain of the monopole antenna and the plasma off were also compared as
shown in Figure 6.11 for the simulation result. Nonetheless, there was not much
reduction in gain with the presence of the surrounding dielectric tubes.
Figure 6.11: Comparison between monopole and plasma off for simulation results gain (dB)
versus frequency (GHz).
These results again confirm that, the presence of dielectric tubes surrounding
the monopole antenna has no significant effects to the reflection coefficient.
Therefore, it is possible to construct a reconfigurable reflector antenna by only
activate and de-activate the plasma elements without having to worry about the effect
of fluorescent tubes.
6.4 SWITCHING PATTERN OF RECONFIGURABLE PLASMA ANTENNA
ARRAY FOR BEAM SCANNING
The concept of creating a reconfigurable plasma antenna array is the energy
source surrounding a plasma blanket in a region where the plasma frequency is less
than the antenna frequency, whereby the antenna radiation passes through the blanket
while in the region, whereby the plasma frequency is higher than the antenna
137
frequency, and the plasma behaves like a perfect reflector. Thus, to create a beam
shaping radiation pattern, not all elements were set as plasma or metal in every
simulation. Generally, a number of deactivated elements (switched OFF) defined and
determined the size of beamwidth of the radiation pattern. As the idea is to have a
sectoral beam shape, only certain of the total elements are working as reflector at a
time (switched ON). Hence, in order to determine the numbers of plasma element to
switch OFF is needed, the analysis of switching scheme was investigated. In this
research, the antenna prototype used 12 plasma elements to control its element state
(ON or OFF) in order to shape the main beam. Since each elements can be controlled
individually, the antenna has huge possibility to shape its beam. Figure 6.12 shows
the sequence of the elements by numbering in clockwise rotation accordingly to a
specific electronic switch.
Figure 6.12: Switching numbering for reconfigurable plasma antenna array.
In this research work, the set up of three configurations had been identified.
First was 1/12 (1 fluorescent tube switched OFF and 11 fluorescent tube switched
ON), second was 3/12 (3 fluorescent tube switched OFF and 9 fluorescent tube
switched ON), and the last one was 5/12 (5 fluorescent tube switched OFF and 7
fluorescent tube switched ON), elements deactivated. Figure 6.13 shows the simulated
results reflection coefficients, S11 for switching pattern of reconfigurable plasma
antenna array. From this figure, the reflection coefficients, S11 for configuration for
3/12 (-28.39 dB) and 5/12 operate (-29.05 dB) at 2.4 GHz while for configuration 1/12
the magnitude of reflection coefficients, S11 is -17.86 dB at resonant frequency 2.2
GHz.
138
Meanwhile, Figure 6.14 illustrates the measured result reflection coefficients,
S11 for switching pattern of reconfigurable beam switching plasma antenna array.
From this figure, the measured result for configuration for 1/12 seems to have a slight
frequency shift to the left and lower value of S11 than of the simulated. The reflection
coefficients, S11 is measured at 2.0 GHz with -14.76 dB and measured reflection
coefficients, S11 for configuration 3/12 the resonant frequency shifted to the right (2.66
GHz) with -13.51 dB. As for configuration 5/12 the measured result at 2.4 GHz is -
16.49 dB which is slightly lower compared to the simulation result. Besides, during all
plasma off the measured result for reflection coefficients, S11 equal to -17.11 dB at
frequency 2.33 GHz.
Figure 6.13: Simulated reflection coefficients, S11 for switching pattern of reconfigurable
plasma antenna array.
Figure 6.14: Measured reflection coefficients, S11 for switching pattern of plasma antenna
array.
139
(a) (b)
Figure 6.15 : Simulated radiation pattern at 2.4 GHz for switching pattern of reconfigurable
plasma antenna array (a) in H-plane and (b) in E-plane.
(a) (b)
Figure 6.16: Measured radiation pattern at 2.4 GHz for switching pattern of reconfigurable
plasma antenna array (a) in H-plane and (b) in E-plane.
Moreover, a few simulations were performed in order to obtain good radiation
pattern. As mentioned before, the number of deactivated elements (switched OFF)
will determine the beamwidth of radiation pattern. As illustrated in figure 6.15, the
configuration of 1-element resulted in omni-directional and does not give influence in
getting beam shaping pattern. Besides, the pattern of radiation pattern for
configuration 1-element is quite similar when all plasma is deactivated (switched
OFF). Figure 6.16 shows the measured result of radiation pattern for switching pattern
of reconfigurable plasma antenna array in H-plane and E-plane at 2.4 GHz. The
maximum gain of reconfigurable plasma antenna array can be obviously seen in H-
plane direction (at ϕ =50º).
140
(a)
(b)
Figure 6.17 : Simulated result for different number of elements in H-plane (ϕ =50 °) (a) Gain
in dBi (b) Directivity in dBi.
Nonetheless, wider beam shape at broadside direction is observed when 3-
elements configuration is deactivated (switched OFF) but the gain (12.39 dBi) and
directivity (12.74 dBi) is lower compared to 5-elements configuration as shown in
Figure 6.17(a) and (b). It is due to broadening radiation effect. Additionally,
configuration of 3-elements shows higher side lobe and back lobe values as compared
to 5-elements configuration. Thus give the gain and directivity lower than 5-elements
configuration.
141
Therefore, from these analyses pertaining to radiation pattern, with the
optimized reconfigurable beam switching plasma antenna array, the 5-elements
configuration provides the radiation pattern at an optimum result. The beam is more
focus while the back lobe and side lobe are lower as compared to 1-elements and 3-
elements configuration and also giving the highest gain (13.04 dBi) and directivity
(13.17 dBi). Thus, there are only 5 elements need to deactivate (switched OFF) at the
same time in order to scan the beam from 0° until 360° degree with target increment
every 30° and the balance is in activate (switched ON). Table 6.3 shows the summary
of switching pattern of reconfigurable plasma antenna array for gain (dBi) and
Directivity (dBi).
Table 6.3:
Summary of switching pattern of reconfigurable plasma antenna array for beam
scanning.
Number of configuration Gain(dBi) Directivity(dBi)
1/12 7.54 8.57
3/12 12.39 12.74
4/12 12.55 12.78
5/12 13.04 13.17
6/12 12.27 12.50
In this investigation, 12 sequences with the optimized reconfigurable plasma
antenna array were analyzed. The sequences are listed in Table 6.4 along with its
corresponding switching setting.
Table 6.4:
Switching setting for reconfigurable plasma antenna array (Blue color represent activated
elements ( switched ON), while white color represent deactivated elements (switched OFF)). Number of
sequence
Design Deactivated elements
(Switched OFF)
Activated elements
(Switch ON)
1
10,11,12,1,2 3,4,5,6,7,8,9
2
11,12,1,2.3 4,5,6,7,8,9,10
142
3
12,1,2,3,4 5,6,7,8,9,10,11
4
1,2,3,4,5 6,7,8,9,10,11,12
5
2,3,4,5,6 7,8,9,10,11,12,1
6
3,4,5,6,7 8,9,10,11,12,1,2
7
4,5,6,7,8 9,10,11,12,1,2,3
8
5,6,7,8,9 10,11,12,1,2,3,4
9
6,7,8,9,10 11,12,1,2,3,4,5
10
7,8,9,10,11 12,1,2,3,4,5,6
143
11
8,9,10,11,12 1,2,3,4,5,6,7
12
9,10,11,12,1 2,3,4,5,6,7,8
As explained in the previous section, the concept of reconfigurable plasma
antenna array when the fluorescent tube is de-activated or plasma OFF state, the
radiation signal from the monopole antenna will escape from the plasma blanket and
when the fluorescent tube is activated or plasma ON state, the radiation signal will be
trapped inside the plasma blanket. Thus, to control the radiation signal at which angle
it will escape, some features were added to the original design to create a user-friendly
device, as the main target is to ease users with the system usage.
The system was operated by using Arduino technology system, whereby users
can use a remote to control, which is the fluorescent tube, when they want to de-
energized (OFF state) or energized (ON state). This allows the user to focus the signal
at their desired angle. As shown in Figure 6.18, this system consisted of 2 black
boxes. One functioned as a transmitter (remote control) and the other functioned as a
receiver. As illustrate in Figure 6.19, the receiver box was connected to the antenna.
Moreover, the signal transmitted from the transmitter box can go up to 10 meters.
Figure 6.18: Remote control and receiver.
144
Figure 6.19 : Photograph of the overall structure of reconfigurable plasma antenna array
integrated with Arduino technology.
On the other hand, Figure 6.20 illustrates the components that make up a
remote. Each component has its very own function to assist in the operation of
reconfigurable plasma antenna. LCD or liquid-crystal display function as a panel
display to display images indicates the response to the command entered. The main
switch is the component that controls to ON and OFF the remote control. Next, is the
LED or light-emitting diode that functions to indicate which fluorescent tube is in ON
or OFF position. The configuration of the fluorescent tubes is portrayed in Figure
6.12. Last but not least, the keypad switch functions to make selection of which
fluorescent tube to be turned ON or off. Switches 1 until 9 represent fluorescent tubes
1 until 9 with clockwise rotation, while switches A, B, C, # and * represent numbers
10, 11, 12, all OFF, and all ON respectively.
.
Figure 6.20 : Remote control with the main components.
145
(a) (b)
Figure 6.21: (a) Circuit at the remote control. (b) Circuit at the receiver.
6.5 SIMULATION AND MEASUREMENT RESULTS OF
RECONFIGURABLE PLASMA ANTENNA ARRAY
The process of simulation and optimization of reconfigurable plasma antenna
array was performed by using CST Microwave Studio. The prototype of
reconfigurable plasma antenna array was successfully fabricated and measured in
order to validate the simulated results. The antenna performance was analyzed in
terms of return loss and its radiation characteristics, including gain, side lobe level,
HPBW, and main lobe direction. To achieve the pattern of reconfiguration, diversity
in the main lobe directions had been the main focus in this antenna design.
.
(a) (b)
Figure 6.22 : Schematic drawing of reconfigurable plasma antenna array. (a) Overall view (b)
Side view.
146
(a) (b)
Figure 6.23: Prototype of the reconfigurable plasma antenna array (a) De-activated (Plasma
off) of 12 fluorescent tubes. (b) 5/12 plasma in ON condition
Figure 6.22 shows the schematic diagram of the fabricated reconfigurable
plasma antenna array from overall view and side view of the antenna. The prototype
of reconfigurable plasma antenna array is shown in Figure 6.23.
In order to steer a beam from 0° to 360°, only 5 elements were need to be
deactivated (Switched OFF) while the rest remained activated (ON state). To ease the
scanning process, each element was numbered by its location in clockwise direction as
shown in Figure 6.13. The ON-OFF sequences to scan were made based on the
switching setting scheme listed in Table 6.3 which has been explained in the earlier
section (switching scheme).
The simulated reflection coefficient, S11 is shown in Figure 6.24. The results
indicated that the patterns for reflection coefficient, S11 were quite similar for all
angles at frequency 2.4 GHz.
Figure 6.24 : Simulated of reflection coefficient, S11.
147
The pattern reconfiguration of reconfigurable plasma antenna array can be
obviously seen in H-plane direction (at ϕ =50º), whereby the main lobe of the co-
polarization is directed to 12 different angles at different switching states at frequency
2.4 GHz, as depicted in Figure 6.25. Therefore, the radiation patterns discussed
hereafter in this section are focused on the results in the H-plane direction due to the
fact that the main lobe direction of the reconfigurable plasma antenna array seems to
have no significant difference in term of angle in E-plane direction regardless of
different switching states. Thus, the E-plane patterns are omitted because they are
always directed towards 53°.
The resulting simulated radiation patterns offered by reconfigurable plasma
antenna array demonstrating the beam steering capability in H-plane directions as
presented in Figure 6.25.
(a) (b)
(c) (d)
148
(e) (f)
(g) (h)
(i) (j)
149
(k) (l)
Figure 6.25: Simulated results of radiation pattern for reconfigurable plasma antenna array at
different switch configuration modes.
The resulting set of radiation patterns demonstrating the beam steering
capability in the H-plane as shown in Figure 6.26. The beam can be directed at desired
direction by switching ON the appropriate numbers of adjacent elements as discussed
in section 6.4. The simulated HPBW is ±64°. Moreover, Figure 6.26 presents the
results from simulation and shows that the main beam directions can be pointed in the
following directions depending on the switch configuration mode: 0°, 30°, 60°, 90°,
120°, 150°, 180°, 210°, 240°, 270°, 300°, 330° and 360°. These results clearly show
that the main beam for the antenna can be steered by changing the switch
configuration.
150
Figure 6.26 : Combination of simulated scanning radiation patterns in the H-plane for
reconfigurable plasma antenna array.
Figure 6.27 exhibits the simulated peak gains (abs) of reconfigurable plasma
antenna array at the operating frequency of 2.4 GHz in Cartesian plots. The plots
clearly illustrate that the reconfigurable plasma antenna array has similar peak gains at
different angles regardless of different switching patterns.
Figure 6.27 : Simulated peak gains (abs) of reconfigurable plasma antenna array with
different main lobe directions at frequency 2.4 GHz.
151
Other simulated radiation characteristics of reconfigurable plasma antenna
array are tabulated in Table 6.5.
Table 5.5:
Simulated radiation characteristics of reconfigurable plasma antenna array
Number
of
sequence
Gain (dB) Directivity
(dBi)
HPBW
(°)
Side lobe level
(dB)
Main lobe
direction (°)
1 13.04 13.17 64.1 -24.3 0/360
2 13.06 13.17 64.0 -23.4 30
3 13.06 13.17 64.0 -23.4 60
4 13.03 13.16 64.1 -24.4 90
5 13.06 13.17 64.1 -23.4 120
6 13.06 13.18 64.0 -23.4 150
7 13.03 13.16 64.0 -24.3 180
8 13.05 13.17 64.0 -23.4 210
9 13.05 13.17 64.1 -23.4 240
10 13.02 13.15 64.0 -24.3 270
11 13.05 13.17 64.1 -23.4 300
12 13.06 13.17 64.1 -23.3 330
(a) (b)
Figure 6.28: Reflection coefficient, S11 (a) Measurement (b) Simulation.
152
Apart from that, to show the flexibility of the antenna design, the impedance of
the antenna has been measured. The impedance of each of the reconfigurable plasma
antenna array elements was measured based on the number of sequence as shows in
Table 6.5. Meanwhile, Figure 6.28 shows the comparison between simulation and
measurement results of S11 when the reconfigurable plasma antenna array is operating
at 12 different numbers of sequences at frequency 2.4 GHz. The measured impedance
data were plotted for each number of sequences as shown in Figure 6.28 (a). It can be
seen that very good agreement was obtained for all number of sequence, with the
measured return loss lower than -10 dB. The results from the simulation seemed to
agree well with the measurement results. Hence, it had been proven that the
reconfigurable plasma antenna array can be operated at a frequency of 2.4 GHz.
As described previously, the design of reconfigurable plasma antenna array
focused on the radiation pattern reconfiguration at a frequency of 2.4 GHz. In other
words, the reconfigurable plasma antenna array had been expected to have pattern
reconfigurabilities. Hence, the measurement for radiation patterns of reconfigurable
plasma antenna array was conducted in an indoor anechoic chamber. The details of the
measurement setup have been explained in the previous chapter.
(a) (b)
153
(c) (d)
(e) (f)
(g) (h)
154
(i) (j)
(k) (l)
Figure 6.29: Simulated and measured radiation pattern in H-plane at frequency 2.4 GHz.
Figure 6.29 exhibits the simulated and the measured radiation pattern in polar
plot at frequency 2.4 GHz. The results clearly show that the reconfigurable plasma
antenna array could be pointed with twelve different steerable beam directions at each
frequency mode, 2.4 GHz (0°,30°,60°,90°,120°,150°,180°,210°,240°,270°,300°, and
330°). The results from the simulation seem to agree well with the measurement
results.
6.6 SUMMARY
In this chapter, the innovative design of reconfigurable antennas had been
described. The design of antenna emphasized on using plasma elements as the
reflector elements instead of using metal elements. The plasma antenna of beam-
155
switching was investigated based upon the interaction of plasma elements due to the
incident of electromagnetic wave.
Moreover, the simulated and the measured data were demonstrated for the
concept of a reconfigurable plasma antenna array that could produce steering beam
pattern characteristics, as presented in this chapter. This chapter also includes a
comparative analysis on the effects of several antenna parameters.
On top of that, good agreement was also achieved between simulation and
measurement results. The results confirmed that the antennas could be steered in
twelve directions, 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and
330°, respectively at frequencies across the entire 2.4 GHz band, with excellent
transmission matching for all configuration modes.
156
CHAPTER SEVEN
CONCLUSION, FUTURE WORKS AND RESEARCH
CONTRIBUTION
7.1 CONCLUSION
This thesis described the design that focused on the theory and the design
using plasma element as a conductor element in antenna application. Three new
antenna designs presented were the cylindrical monopole plasma antenna, monopole
plasma antenna using fluorescent tube, and reconfigurable plasma antenna array. This
project involved antenna design simulation, fabrication, and measurement processes in
order to develop a new antenna design based on plasma medium instead of metallic
medium. Furthermore, Computer Simulation Technology (CST) Studio Suite software
packages have been employed to obtain the characteristics of the respective designed
antennas.
In the beginning of this thesis, a brief review of plasma has been discussed and
explained. Next, in chapter 2 provides a review of previous work and information
related to plasma antenna. Besides, explanation about theoretical equation plasma
parameters was presented in chapter 3. Also included in this chapter is estimation of
plasma frequency and collision frequency. Hence, it is necessary to estimate the value
of these two parameters. Thus, several experiments were conducted to obtain
approximations for plasma frequency and collision frequency.
Meanwhile, chapter 4 depicts the investigation and analyses of the interaction
between plasma behaviors to RF signal. The cylindrical monopole plasma antenna
with three different types of gases; argon gas, neon gas and Hg-Ar gas were simulated
and measured. The performances of cylindrical monopole plasma antenna had been
validated and it was proven that plasma parameters did influence the performances of
the antenna. Therefore, when the pressure was increased with the same type of gas,
the collision frequency and the electron density also increased. When collision
frequency was higher, the conductivity became lower, and thus, the gain decreased. In
addition, the value of antenna gains also affected by size and mass of atom. When the
157
size and mass of atom is increase, the gain will be decrease. The measured radiation
patterns were in good agreement with the simulation ones.
On top of that, in chapter 5, by using commercial fluorescent tube, a monopole
plasma antenna was fabricated and measured at 2.4 GHz. Based on the measurement
results, it can be concluded that the commercial fluorescent tube with a coupling
technique could be used to radiate radio signals. The radiation pattern of monopole
plasma antenna measured at frequency 2.4 GHz showed that the pattern had been
quite similar to the radiation pattern for classic monopole antenna. Thus, the findings
of this study indicated that the plasma antenna could be considered as a monopole
antenna. Besides, the results from the measurements for each structure seemed to
agree well with the simulation results.
In Chapter 6, the development of a new structure of pattern reconfigurable
antennas was described and investigated, namely reconfigurable plasma antenna array.
A reconfigurable plasma antenna array was developed with commercial fluorescent
tube as a plasma element and it functioned as a reflector medium when plasma
frequency was greater than the operating frequency. The significant function of the
antenna was to produce twelve different beam-steering angles at frequency 2.4 GHz.
This means, the main lobe of the radiation pattern of reconfigurable plasma antenna
array can be directed to 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°,
and 330°, with twelve direction and respectively at frequencies across the entire 2.4
GHz band, with excellent transmission matching for all the configuration modes.
Moreover, the simulated and the measured data were demonstrated for the concept of
a reconfigurable plasma antenna array that could produce steering beam pattern
characteristics, as presented in this chapter. This chapter also includes a comparative
analysis on the effects of several antenna parameters.
Overall, the proposed antenna designs have achieved the objectives of this
thesis. The problems highlighted at the beginning of this thesis have been successfully
solved. In the following section, some possible improvement to the work performed in
this research and possible avenues for further studies are presented.
158
7.2 FUTURE WORKS
Based on the works done on plasma antenna in this research, the following are
some other prospective studies that can be carried out in future research.
7.2.1 Different types of gases
This research only focused on three types of gases; Argon, Neon, and Hg-Ar.
The reason for only three gases introduced in this research had been because of the
limitation in material. Thus, by having different types of gases, such Helium and
Nitrogen with a variety of different pressures, many plasma parameters can be
analyzed.
7.2.2 Operating Frequency
In Chapter 5, the monopole plasma antenna using fluorescent tube was proven to
work at a frequency of 2.4 GHz. Hence, this antenna can also be designed and
fabricated to operate at other frequencies, such as at 5.8 GHz for WiMAX application.
A new plasma model has to be developed in order to accommodate the loss sensitivity
in plasma
7.2.3 Different shape of plasma antenna
In this thesis, the fluorescent tube that was used had been in cylindrical shape.
The monopole plasma antenna and reconfigurable plasma antenna array can also be
designed by using different shapes of fluorescent lamp, such as U shape and circle
shape.
7.3 RESEARCH CONTRIBUTION
Three contributions that are significant to plasma antenna technology have been
identified in this research. Those are:
159
1. Identification of relationship between plasma parameter and microwave
characteristic which can serve as guideline in future plasma antenna research.
2. Invention of new device with multi-function; lighting emitting device with
antenna functioned.
3. Designing a reconfigurable antenna that use plasma element as a reflector
antenna whilst other conventional reconfigurable antenna use metal element.
160
REFERENCES
[1] J.Hettinger, “Aerial Conductor for Wireless Signaling and Other Purposes,”
U.S patent number 1309031, July 1919.
[2] J. Zhou, J. Fang, Q. Lu, and F. Liu, “Research on Radiation Characteristic of
Plasma Antenna through FDTD Method,” The Scientific World Journal, vol.
2014, no. 2, pp 1-8, 2014.
[3] D.Kumar and R.A Bora, “Wireless communication capability of a
recornfigurable plasma antenna,” Journal Application on Physics, vol. 109, no.
6, pp 1-9, 2011.
[4] X. P. Wu, J.-M. Shi, Z. S. Chen, and B. Xu, “A New Plasma Antenna Of
Beam-Forming,” Progress In Electromagnetics Research, vol. 126, no. 2, pp.
539–553, 2012.
[5] A. Zhu, Z. Chen, and J. Lv, “Reconfigurable Characteristics of the Monopole
Plasma Antenna and Its Array Driven by Surface Wave,” WSEAS Transactions
On Communications, vol. 12, no. 4, pp. 143–153, 2013.
[6] Z. Dai, S. Liu, Y. Chen, and N. Gao, “Development and Investigation of
Reconfigurable Plasma Antennas,” in Microwave and Millimeter Wave
Technology (ICMMT), 2010 International Conference, no. 29, pp. 1135–1137,
2010.
[7] E. Vecchioni, G. Cerri, P. Russo, and V. M. Primiani, “Experimental and
Theoretical Investigation on Plasma Antennas,” Journal Applied Physics, vol.
30, pp. 3–6, 2013.
[8] B.Constantine A, Antenna Theory: Analysis and Design, USA, 3rd
ed,: John
Wiley & Sons, 2005.
[9] S. Nikolaou, R. Bairavasubramanian, S. Member, C. Lugo, I. Carrasquillo, D.
C. Thompson, G. E. Ponchak, S. Member, J. Papapolymerou, and M. M.
Tentzeris, “Pattern and Frequency Reconfigurable Annular Slot Antenna Using
PIN Diodes,” IEEE Transaction on Antenna and Propagation, vol. 54, no. 2,
pp. 439–448, 2006.
[10] S. S. Yang, A. A. Kishk, and K. Lee, “Frequency Reconfigurable U-Slot
Microstrip Patch Antenna,” IEEE Antenna and Wireless Propagation Letter,
vol. 7, pp. 127-129, 2008.
161
[11] D. Rodrigo and S. Member, “Frequency and Radiation Pattern
Reconfigurability of a Multi-Size Pixel Antenna,” IEEE Transaction on
Antenna and Propagation, vol. 60, no. 5, pp. 2219-2225, 2012.
[12] R. A. Lewis, “Wideband Antenna Technology in Military Applications,” in
International Workshop Antenna Technology, pp. 2–5, 2010.
[13] R. G. Patil, A. Mukherjee, and A. B. Nandgaonkar, “Design of Broadband Two
Layer Stacked Microchip Antenna With a Folded Plate Pair for Military Band
Applications,” in International Emerging Trends in Network and Computer
Communication, pp. 418–420, 2011.
[14] F. Rashid, M. Mustafiz, M. K. Ghosh, and S. Hossain, “Design and
Performance Analysis of Ultra Wideband Inverted-F Antenna for Wi-Fi ,
WiMAX , WLAN and Military Applications,” in International Conference on
Computer and Technology, pp. 610–614, 2012.
[15] M.J. Rana and M.A.S.Mollah, “Numerical Study of a Loaded U-Antenna for
3.5 GHz Mobile WiMAX 7.5 GHz Millitary Satellite Communication
Applications,” in International Conference Computer and Information
Technology, pp. 8–10, 2014.
[16] P. Punjab, “The New World of Plasma Antennas,” Electronic For You, pp.
106–110, August 2011.
[17] P.A. Mellan, "Fundamentals of Plasma Physics", Pergamon Press, pp. 1–
10,2004
[18] A.Aurius, “The fourth state of matter.” [Online]. Available:
http://cidocido.hubpages.com/hub/They-taught-you-wrong-theres-way-more-
than-solid-liquid-gas [Accessed : 24-January 2015].
[19] “Ionization a physical process with many useful applications.” [Online].
Available:http://inventorspot.com/articles/ionization_physical_process_many_u
seful_applications [ Accessed : 21- February 2015] .
[20] E.Norris, T.Anderson, and I.Alexeff, “Reconfigurable Plasma Antenna,” IEEE
Transaction on Antenna and Propagation, vol. 50, no. 3, pp. 439–448, 2010.
[21] J. R. Roth, Industrial Plasma Engineering, USA 2nd
ed: Institute of
Physics(IOP), 1995.
[22] C. H. Zhang, S. Katsuki, H. Horta, H. Imamura, Y. Kondo, T. Namihira, and H.
Akiyama, “Xenon Discharge Produced Plasma Radiation Source for EUV
162
Lithography,” IEEE Transaction on Antenna and Propagation, vol. 21, no 3,pp.
2320–2323, 2005.
[23] A. N. Dagang, “Analysis of Electrode-less Discharges and Their Application in
Developing Mercury-free Light Sources Analysis of Electrode-less Discharges
and Their Application in Developing Mercury-free Light Sources,” IEEE
Transaction on Plasma Science, vol. 21, no 3,pp. 2320–2323, 2007.
[24] A. Bogaerts, E. Neyts, R. Gijbels, and J. Van Der Mullen, “Gas discharge
plasmas and their applications,” IEEE Transaction on Antenna and
Propagation, vol. 57, pp. 609–658, 2002.
[25] M. Chung, W.S. Chong, W.S. Chen, Y.Horng, Y. Y.Hiang. C.Yu, and Z.Y.
Liou, “Properties of DC-biased plasma antenna,” in International. Conference
Microwave Technology., vol. 3, no. 1, pp. 8–10, 2008.
[26] P. Walker, "Plasma Antenna Radiation Pattern, " Progress In Electromagnetics
Research Letters, vol. 24, no.2, pp. 17–26, May 2011.
[27] L. Zheng, L. Cao, and Z. Zhang, “Study on the Gain of Plasma Antenna,” in
International Symposium on Antenna Propagation and EM Theory, pp. 222-
224, November 2008.
[28] W.Hittorf, “Ueber die electricitatsleitung der gase,” Application Jornal Physics,
vol. 21, no. 3, pp. 137–139, 1994.
[29] J. J. Thomson, “On The Discharge Of Electricity Through Exhausted Tubes
Without Electrodes,” Applied Physics Journal, vol. 32,no. 3, pp. 321–336,
1991.
[30] D. O. Wharmby, “Electrodeless Lamps For Lighting,” IEEE Plasma Physics
Journal, vol. 140, no. 4, pp. 465–473, 1993.
[31] K. Bera, S. Rauf, A. Balakrishna, and K. Collins, “Plasma-Profile Control
Using External Circuit in a Capacitively Coupled Plasma Reactor,”
International Journal for Apply Physics, vol. 38, no. 11, pp. 3241–3248, 2010.
[32] P. I. V France and E. Abb, “Dielectric-Barrier Discharges. Principle and
Applications,” International Journal on Electron Mobility, vol. 7, no. 1,pp 997-
1009, 1997.
[33] X.Y. Dong, Z.L. Xiu, S. Li, Y.-M. Hou, D.J. Zhang, and C.-S. Ren, “Dielectric
barrier discharge plasma as a novel approach for improving 1,3-propanediol
163
production in Klebsiella pneumoniae.,” Biotechnology Letter, vol. 32, no. 9, pp.
1245–50, Sep. 2010.
[34] Y. Sakamoto, S. Maeno, N. Tsubouchi, T. Kasuya, and M. Wada, “Comparison
of Plasma Parameters in CCP and ICP Processes Appropriate for Carbon
Nanotube Growth,” International Journal Application Physics in Plasma,vol. 8,
no. 3, pp. 587–590, 2009.
[35] J. H. Kim, Y. C. Hong, H. S. Kim, and H. S. Uhm, “Simple Microwave Plasma
Source at Atmospheric Pressure,” Journal of Electromagnetic Analysis and
Application, vol. 42, no. 2, pp. 876–879, 2003.
[36] P. Russo, V. M. Primiani, G. Cerri, R. De Leo, and E. Vecchioni,
“Experimental Characterization of a Surfaguide Fed Plasma Antenna,” IEEE
Transaction Antennas Propagation., vol. 59, no. 2, pp. 425–433, 2011.
[37] H. Cheng, O. Ronald and C.Heng “Design and simulation for the experiment
system of plasma antennas,” International Journal for Applied Physics, no. 5,
pp. 1272–1275, 2012.
[38] J. W. Lveng,Y. S. Li, and Z. L. Chen, “Numerical Modelling of Cylindrical
Monopole Plasma Antenna Excited By Surface Wave,” Journal of Physics, vol.
2,no 3, pp. 21–27, 2012.
[39] A. Zhu, “Characteristics of AC-biased Plasma Antenna and Plasma Antenna
Excited by Surface Wave,” Journal Electromagnetic Analytical and
Application., vol. 4, no. 7, pp. 279–284, 2012.
[40] R. Kumar and D. Bora, “Experimental Study of Parameters of a Plasma
Antenna,” Institute of Physics, vol. 592, no 3,pp 234-240,2012.
[41] M. Dwyer, T.J., Greig, J.R., Murphy, D.P., Perin, J.M., Pechacek, R.E., and
Raleigh, “On the FeasibiUty of Using an Atmospheric Discharge Plasma as an
RF Antenna,” IEEE Transaction. Antennas Propagation., vol. 32, no.2,pp 126-
129,2013.
[42] M. Alshershby and J. Lin, “Air by Laser-induced Filaments : Passive Radar
Application,” Journal Electromagnetic Analytical and Application, vol.2,no.3,
pp. 23–25, 2012.
[43] A.Couairon and A.Mysyrowicz, “Femtosecond filamentation in transparent
media,” Journal Physics Application., vol. 441, no. 2, pp. 47–189, Mar. 2007.
164
[44] T.Anderson, “Plasma Antenna Application", Article in Artech House, pp.156-
157, 2011.
[45] T. Anderson, “Static Satellite Plasma Antenna Experiment,” Electronic and
Physics Letter, vol.2,no 3, pp. 1–25,2009.
[46] J. S. Zhao, Z. T. Zhang, Y. J. Li, S. J. Xu, J. Yao, Y. P. Tian, and Z. Yu,
“Radiation Characteristics And Electromagnetic Compatibility Of 5-20 Khz Ac
Plasma Antenna,” Journal Physics and Plasma., vol. 418, pp. 569-576, Mar.
2013.
[47] T. Anderson," Application on Plasma Antennas." International Journal on
Application Physics, vol. 3, no. 4,pp. 38–39,2011.
[48] J. P. River, A. Dheng, C. G. Neong, F. A. Ping and W. M. Hargreave,
“Coupling Power and Information to a Plasma Antenna,” in Proceeding of the
11th International Congress on Plasma Physics, pp. 388–391,2010.
[49] G. Cerri, R. De Leo, V. M. Primiani, and P. Russo, “Measurement of the
Properties of a Plasma Column Used as a Radiating Element,” IEEE
Transaction on Instrumentation and Measurement, vol. 57, no. 2, pp. 242–247,
2008.
[50] P. Darvish, B.Zakeri and A. Gorji, “Studying Different Couplers for a Basic
Plasma Antenna,” in IEEE International Conference Communication, pp. 5–
9,2010.
[51] M. Liang and G. Qinggong, “FDTD Analysis of a Plasma Helix Antenna,” in
International Conference on Microwave and Milimeter Wave Technology , pp.
1854–1857, 2008.
[52] Z. H. Qian, K. W. Leung, R. S. Chen, and D. X. Wang, “ Plasma Antenna
Radiation Pattern in Communication System," International Journal of Science
and Technology, vol. 3, no. l, pp. 166–169, 2005.
[53] F. Mohd and F. Etesami, “On Radiation Characteristics of a Plasma Triangular
Monopole Antenna,” in The 19th Iranian Conference Electrical Engineering
(ICEE), pp 565-570, 2011.
[54] J. Bernhard and M.Richard, “Reconfigurable Antennas And Apertures: State-
Of-The-Art And Future Outlook,” Proceding SPIE Conference Smart
Electron. MEMS, BioMEMS, Nanotechnol., vol. 5055, pp. 1–9, 2003.
165
[55] E.Brown, N.K.Wong and I.Friencie “On The Gain Of A Reconfigurable-
Aperture Antenna,” IEEE Transaction Antennas Propagation., vol. 49, pp.
357–1362,2007.
[56] T. Anderson, “Static Satellite Plasma Antenna Experiment,” Electronic and
Physics Letter, vol.2,no 3, pp. 1–25,2009.
[57] D. B. Rajneesh kumar and K.Kulam, “A Reconfigurable Plasma Antenna,”
Journal Application Physics 2, vol. 107,no 2,pp 356-360, 2010.
[58] A. Kallel, J. Sokoloff, and T. Callegari, “Theory and Simulations of a Beam-
Scanning Plasma Antenna,” in International Conference of Physics and
Application to Communication System, pp. 3457–3461, 2013.
[59] T. T. Anderson, “Theory , Measurements , and Prototypes of Plasma
Antennas,” in IEEE International Conference of Physics, pp. 567–568, 2014.
[60] M. Taufiq, O. Lafond, F. Colombel, and M. Himdi, “Performance and
Radiation Patterns of a Recon fi gurable Plasma Corner-Reflector Antenna,”
IEEE Antenna Wireless and Propgation Letter, vol. 12, no. 1, pp. 1137–1140,
2013.
[61] C. D. Lorrain and P.Brityei, Electromagnetic Fields and Waves, USA 2nd
edition. John Wiley& Sons, 1976.
[62] Alexander Fridman and Lawrence A.Kennedy, Plasma Physics and
Engineering. France 1st edition:Taylor & Francis, 2004.
[63] G. G. Lister and S. E. Coe, “GLOMAC : A One Dimensional Numerical Model
For Steady State Low Pressure Mercury-Noble Gas Discharges,” Computer
Physic Communication, vol. 75, no. 2, pp. 160–184, Apr. 1993.
[64] S. T. Henderson, Lamps and Lighting. 2nd
ed: Edward Arnold Ltd, 1972.
[65] O. Sylvania and J. E. Lawler, “The Physics Of Discharge Lamps,” Journal of
Science Technology, vol. 76, no.4, April 2004.
[66] “3D EM field simulation-CST computer simulation technology.” [Online].
Available: http://www.cst.com,[Accessed: 20- Novemebr 2013].
[67] U. Kogelschatz, B. Eliasson, W. Egli, and W. Dutvhy , “Dielectric-Barrier
Discharges . Principle and Applications" in International Conference of Physic
and Technology,” pp. 367-370,1997.
166
[68] T.Hilary,G.H.Loirey and T. Firnai, “Effects of Coupling Sleeve Designs on a
RF Charged Plasma Monopole Antenna,” International Journal of System
Engineering, vol. 3, no. 600, pp. 3–6, 2012.
[69] C. C. Motta, A. D. Fonseca, G. H. Gomes, and H. S. Maciel, “Complex
Permittivity Measurement in Dielectric Waveguide Filled with Argon Plasma,”
in International Conference of System and Application ,pp. 273–276, 2001.
[70] T. Al-Maznaee and H.E. Abd-El-Raouf, “Design of reconfigurable patch
antenna with a switchable V-Slot,” Progres in Electromagnetic Research. C,
vol. 6, pp. 145–158, 2009.
[71] S. T. Henderson, Lamps and Lighting. 1st ed:Edward Arnold Ltd, 1972.
72] D. L. Rossa. and W. Ping and R. E. Clementi, “Atomic Screening Constants
from SCF Functions. II. Atoms with 37 to 86 Electrons,” Journal Chemistry
and. Physics, vol. Vol. 47, no. No 4, pp. pp. 1300–1307, 1967.
[73] G. H. Aylward and T. J. V. Findlay, SI Chemical Data, 4th Edition. Wiley
&Sons, 1999.
[74] J. E. Harry, Introduction to Plasma Technology: Science, Engineering and
Applications. 1st ed:Wiley&Sons, 2010.
[75] P. Russo, G. Cerri, and E. Vecchioni, “Self-consistent model for the
characterisation of plasma ignition by propagation of an electromagnetic wave
to be used for plasma antennas design,” IET Microwaves, Antennas
Propagation., vol. 4, no. 12, p. 2256, 2010.
[76] M. Klick, L. Eichhorn, W. Rehak, M. Kammeyer, and H. Mischke, “Influence
of excitation frequency on plasma parameters and etching characteristics of
radio-frequency discharges,” Journal of Surf. Coatings Technology., vol. 116–
119,no 3, pp. 468–471, 1999.
[77] R. Nicloy and Q.Keyl, “Plasma Sources Based on The Ppropagation of
Electromagnetic Surface Waves,” Journal of Science Technology, vol. 24, pp.
1025–1048, 1991.
[78] G. G. Borg, J. H. Harris, D. G. Miljak, and N. M. Martin, “Application of
Plasma Columns To Radiofrequency Antennas,” Journal of Plasma Physics,
vol. 74, no. 22, pp. 3272–3274, 2014.
167
[79] M. C. M. Chung, and W. Suen, “Capacitive coupling return loss of a new pre-
ionized monopole plasma antenna,” in Conference of Technology in
Communication System (TENCON 2007), pp. 3–6, 2007.
[80] U. I. Balynis and R.Henry, “Plasma antenna with mercury filling,” Journal of
Pasma Physics, vol 3,no. 1, pp. 167–169, 2012.
[81] B. Bowers, L. Symons, and N. Alding, “Electric Light Source,” Journal of
Lighting in Science, vol 3, no 3, pp. 4–10, 1995.
[82] B. L. J. Davies, B. Scyr, H. R. Ruff, A. Member, and W. J. Scott, “Fluorescent
Lamp in Neon ,” in Conference of Lighting System,pp 233-236, 1942.
[83] S.T. Henderson and A. M. Marsden,"Advantages of Hg-Ar Lamps" in
Conference of Lamps and Lighting Application. pp 117-120,1972.
[84] “Fluorescent lighting,” Cannabis.com, 2014. [Online]. Available:
http://www.cannabis.com.[Accessed: 23-November 2014]
[85] J. H. and P. H. Alexeff, I.T Anderson, S.Parameswaran, E.P Pradeep,
“Experimental and Theoretical Results With Plasma Antennas,” IEEE
Transaction. Plasma Science., vol. 34,no 2, pp. 101-108, 2006.
[86] G.Walker,D.Dilson and F.Koiiry, “Advantages of Using Electronic Ballasts,” in
Conference of Electrical Power Engineering, pp. 4–10, 2001.
[87] F. Sadeghikia, “The Effects of the Tube Characteristics on the Performance of a
Plasma Monopole Antenna,” Journal of Plasma Physics,vol. 1, no. 1, pp. 1208–
1211, 2012.
[88] D. Qian, D. Jun, G. U. O. Chen-jiang, and S. H. I. Lei, “On Characteristics of a
Plasma Column Antenna,” in Confrenece of Asia Pacific Microwave
COmmunication,pp. 622-625,2007.
[95] U.Kogelschatz, “Dielectric-barrier discharges: Their History, Discharge
Physics, and Industrial Applications,” Plasma Chemistry and Plasma
Processing, vol. 23. pp. 1–46, 2003.
[96] R. Li, Y. Yamaguchi, S. Yin, Q. Tang, and T. Sato, “Influence of dielectric
barrier materials to the behavior of dielectric barrier discharge plasma for CO2
decomposition,” in Solid State Ionics, 2004, vol. 172, pp. 235–238.
[97] X. Xu, “Dielectric barrier discharge: Properties and applications,” Thin Solid
Films Articles, vol. 3,no 1, pp. 237–242, 2001.
168
[98] H. Conrads and M. Schmidt, “Plasma Generation and Plasma Sources,” Plasma
Sources Science and Technology, vol. 9, no.2, pp. 441–454, 2000.
[99] H. Q. Ye, M. Gao, and C. J. Tang, “Radiation Theory Of The Plasma Antenna,”
IEEE Transaction Antennas Propagation, vol. 59, no 5, pp. 1497–1502, 2011.
[100] N. G. Gusein-zade, I. M. Minaev, and K. Z. Rukhadze, “Plasma Receiving
Dipole Antenna,” Bulletin of the Lebedev Physics Institute, vol. 37. no. 2 pp.
58–59, 2010.
[101] Y. S. Chen, S. Y. Chen, and H. J. Li, “Analysis of antenna coupling in near-
field communication systems,” IEEE Transaction Antennas and Propagation.,
vol. 58, no 1, pp. 3327–3335, 2010.
[102] I. Alexeff, T. Anderson, S. Parameswaran, E. P. Pradeep, J. Hulloli, and P.
Hulloli, “Plasma Antennas Application,” IEEE Transaction Plasma Science,
vol. 34, no. 3, pp. 166–172, 2006.
[103] T. Anderson, I. Alexeff, E. Farshi, N. Karnam, E. P. Pradeep, N. R. Pulasani,
and J. Peck, “An Operating Intelligent Plasma Antenna,” in 16th IEEE
International Pulsed Power Conference., pp 455-458, 2007.
[104] T. Anderson, I. Alexeff, J. Raynolds, E. Farshi, S. Parameswaran, E. P.
Pradeep, and J. Hulloli, “Plasma Frequency Selective Surfaces,” IEEE
Transaction Plasma Science., vol. 35, no.2,pp 1222-1230, 2007.
[105] T. Anderson, “Plasma Devices For Steering And Focusing Antenna Beams”,
US Patent: 841340, 2013.
[106] D. Han, H.-C. Lee, H. J. Kim, Y. S. Kim, C.-W. Chung, and H. Chae, “Effects
Of Capacitor Termination To An Antenna Coil On The Plasma Parameters In
A Radio Frequency Inductively Coupled Plasma,” Plasma Sources Science.
Technology, vol. 22, no 2, pp. 344-350, 2013.
[107] J. P. Rayner, A. P. Whichello, and A. D. Cheetham, “Physical characteristics of
plasma antennas,” IEEE Transaction. Plasma Science., vol. 32, no 3, pp. 269–
281, 2004.
[108] F. F. Chen, “Plasma Ionization By Helicon Waves,” Plasma Physics and
Controlled Fusion Journal, vol. 33, no. 4, pp. 339–364, 2000.
[109] P. B. Corkum, “Plasma Perspective on Strong-Field Multiphoton Ionization,”
Physics. Revision. Letter, vol. 71, no. 3, pp. 1994–1997, 1993.
169
[110] C. L. O’Connell, C. D. Barnes, F. J. Decker, M. J. Hogan, R. Iverson, P.
Krejcik, R. Siemann, D. R. Walz, C. E. Clayton, C. Huang, D. K. Johnson, C.
Joshi, W. Lu, K. A. Marsh, W. Mori, M. Zhou, S. Deng, T. Katsouleas, P.
Muggli, and E. Oz, “Plasma Production Via Field Ionization,” Physics.
Revision. Spectrum. Technology, vol. 9, no. 3, pp 786-793, 2006.
[111] M. G. Kong, B. N. Ganguly, and R. F. Hicks, “Plasma Jets and Plasma
Bullets,” Plasma Sources Science and Technology, vol. 21, no 3, pp. 201-210,
2012.
[112] X.M. Zhu, W.C. Chen, and Y.K. Pu, “Gas Temperature, Electron Density And
Electron Temperature Measurement In A Microwave Excited Microplasma,”
Journal of Physics D: Applied Physics, vol. 41. No 3, pp. 105-117, 2008.
[113] S. Hofmann, A. F. H. van Gessel, T. Verreycken, and P. Bruggeman, “Power
Dissipation, Gas Temperatures And Electron Densities Of Cold Atmospheric
Pressure Helium And Argon RF Plasma Jets,” Plasma Sources Science and
Technology, vol. 20. No. 3,pp. 650-660, 2011.
[114] D. Lin, W. Yan, and S. Y. R. Hui, “Modeling of Dimmable Fluorescent Lamp
Including The Tube Temperature Effects,” IEEE Transaction. Induction
Electron., vol. 58,no.3, pp. 4145–4152, 2011.
[115] Hyun-Sung Tae, Hyeong-Seok Jang, Soo-Ji Lee, Wang-Sang Lee, and Jong-
Won Yu, “3-Mode Reconfigurable Beam-Forming Array Antenna for Mobile
WLAN Application,” in Microwave Conference (EuMC), 42nd European, pp.
711–714. 2002.
[116] Z. G. Xia, Z. Shen, C. W. Domier, and N. C. Luhmann, “Planar Antenna
Development For Plasma Imaging Application,” in 31st International
Conference on Infrared and Millimeter Waves and 14th International
Conference on Terahertz Electronics, pp 233-237.2002.
[117] S. V. S. Nair and M. J. Ammann, “Reconfigurable Antenna With Elevation and
Azimuth Beam Switching,” IEEE Antennas Wireless. Propagation Letter., vol.
9, no. 1, pp. 367–370, 2010.
[118] P. J. Cargill, “Fundamentals of Plasma Physics,” Plasma Physics and
Controlled Fusion, vol. 49, no. 3, pp. 197–199, 2007.
[119] K. Takayama and A. Tonegawa, “Introduction to Plasma Physics,” Journal of
Advanced Science, vol. 5, no. 3, pp. 11–14, 1993.
170
[120] H. E. Porteanu, S. Kuhn, and R. Gesche, “Low-Power Microwave Plasma
Conductivity,” IEEE Transaction. Plasma Science, vol. 37, no. 3, pp. 44–49,
2009.
.
171
APPENDICES
172
APPENDIX A Measurement of Positive Column, PC
173
APPENDIX B Data Sheet (Philips Fluorescent Lamp)
174
APPENDIX C Data Sheet Electronic Ballast
175
APPENDIX D Delta T
176
APPENDIX E Temperature Vs Vapor Pressure
177
APPENDIX F Periodic Table
178
APPENDIX G SMA Connector
179
APPENDIX H DC Block
180
APPENDIX I Aluminium Tape Datasheet
181
APPENDIX J
Circuit Diagram For Transmitter
182
APPENDIX K
Circuit Diagram for Receiver
183
APPENDIX L
Programming For Transmitter:
#include <Keypad.h>
#include <VirtualWire.h>
#include <LiquidCrystal.h>
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);
const byte ROWS = 4; //four rows
const byte COLS = 4; //three columns
char keys[ROWS][COLS] =
'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;
byte rowPins[ROWS] = 18, 19, 20, 21; //connect to the row pinouts of the keypad
byte colPins[COLS] = 14, 15, 16, 17; //connect to the column pinouts of the keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
char *controller;
int L1,L2,L3,L4,L5,L6,L7,L8,L9,L0,LA,LB,LC,LD,LH,LS;
int led11 = 52;
int led10 = 50;
int led9 = 48;
int led8 = 46;
int led7 = 44;
int led6 = 42;
int led5 = 40;
int led4 = 38;
int led3 = 36;
int led2 = 34;
int led1 = 32;
int led12 = 30;
int ledsignal = 26;
void setup()
pinMode(ledsignal ,OUTPUT);
vw_set_ptt_inverted(true); //
vw_set_tx_pin(12);
vw_setup(4000);// speed of data transfer Kbps
L1=0;
L2=0;
L3=0;
L4=0;
L5=0;
184
L6=0;
L7=0;
L8=0;
L9=0;
LA=0;
LB=0;
LC=0;
LS=0;
LH=0;
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);
pinMode(led4, OUTPUT);
pinMode(led5, OUTPUT);
pinMode(led6, OUTPUT);
pinMode(led7, OUTPUT);
pinMode(led8, OUTPUT);
pinMode(led9, OUTPUT);
pinMode(led10, OUTPUT);
pinMode(led11, OUTPUT);
pinMode(led12, OUTPUT);
digitalWrite(led1, HIGH);
digitalWrite(led2, HIGH);
digitalWrite(led3, HIGH);
digitalWrite(led4, HIGH);
digitalWrite(led5, HIGH);
digitalWrite(led6, HIGH);
digitalWrite(led7, HIGH);
digitalWrite(led8, HIGH);
digitalWrite(led9, HIGH);
digitalWrite(led10, HIGH);
digitalWrite(led11, HIGH);
digitalWrite(led12, HIGH);
digitalWrite(ledsignal, HIGH);
lcd.begin(16, 2);
lcd.print("RF Remote CTRL");
void loop()
char key = keypad.getKey();
if (key)
if (key=='1')
if (L1==0)
L1=1;
lcd.setCursor(0,1);
lcd.print("Lamp 1: ON ");
digitalWrite(led1, LOW);
185
controller="1n";
else
L1=0;
lcd.setCursor(0,1);
lcd.print("Lamp 1: OFF ");
digitalWrite(led1, HIGH);
controller="1f";
if (key=='2')
if (L2==0)
L2=1;
lcd.setCursor(0,1);
lcd.print("Lamp 2: ON ");
digitalWrite(led2, LOW);
controller="2n";
else
L2=0;
lcd.setCursor(0,1);
lcd.print("Lamp 2: OFF ");
digitalWrite(led2, HIGH);
controller="2f";
if (key=='3')
if (L3==0)
L3=1;
lcd.setCursor(0,1);
lcd.print("Lamp 3: ON ");
digitalWrite(led3, LOW);
controller="3n";
else
L3=0;
lcd.setCursor(0,1);
lcd.print("Lamp 3: OFF ");
digitalWrite(led3, HIGH);
controller="3f";
if (key=='4')
if (L4==0)
L4=1;
lcd.setCursor(0,1);
lcd.print("Lamp 4: ON ");
digitalWrite(led4, LOW);
controller="4n";
else
L4=0;
lcd.setCursor(0,1);
lcd.print("Lamp 4: OFF ");
digitalWrite(led4, HIGH);
controller="4f";
186
if (key=='5')
if (L5==0)
L5=1;
lcd.setCursor(0,1);
lcd.print("Lamp 5: ON ");
digitalWrite(led5, LOW);
controller="5n";
else
L5=0;
lcd.setCursor(0,1);
lcd.print("Lamp 5: OFF ");
digitalWrite(led5, HIGH);
controller="5f";
if (key=='6')
if (L6==0)
L6=1;
lcd.setCursor(0,1);
lcd.print("Lamp 6: ON ");
digitalWrite(led6, LOW);
controller="6n";
else
L6=0;
lcd.setCursor(0,1);
lcd.print("Lamp 6: OFF ");
digitalWrite(led6, HIGH);
controller="6f";
if (key=='7')
if (L7==0)
L7=1;
lcd.setCursor(0,1);
lcd.print("Lamp 7: ON ");
digitalWrite(led7, LOW);
controller="7n";
else
L7=0;
lcd.setCursor(0,1);
lcd.print("Lamp 7: OFF ");
digitalWrite(led7, HIGH);
controller="7f";
if (key=='8')
if (L8==0)
L8=1;
lcd.setCursor(0,1);
lcd.print("Lamp 8: ON ");
digitalWrite(led8, LOW);
187
controller="8n";
else
L8=0;
lcd.setCursor(0,1);
lcd.print("Lamp 8: OFF ");
digitalWrite(led8, HIGH);
controller="8f";
if (key=='9')
if (L9==0)
L9=1;
lcd.setCursor(0,1);
lcd.print("Lamp 9: ON ");
digitalWrite(led9, LOW);
controller="9n";
else
L9=0;
lcd.setCursor(0,1);
lcd.print("Lamp 9: OFF ");
digitalWrite(led9, HIGH);
controller="9f";
if (key=='0')
if (L0==0)
L0=1;
lcd.setCursor(0,1);
lcd.print("ERR: BTN 0 ");
controller="0n";
else
L0=0;
lcd.setCursor(0,1);
lcd.print("ERR: BTN 0 ");
controller="0f";
if (key=='A')
if (LA==0)
LA=1;
lcd.setCursor(0,1);
lcd.print("Lamp 10: ON ");
digitalWrite(led10, LOW);
controller="An";
else
LA=0;
lcd.setCursor(0,1);
lcd.print("Lamp 10: OFF ");
digitalWrite(led10, HIGH);
controller="Af";
if (key=='B')
188
if (LB==0)
LB=1;
lcd.setCursor(0,1);
lcd.print("Lamp 11: ON ");
digitalWrite(led11, LOW);
controller="Bn";
else
LB=0;
lcd.setCursor(0,1);
lcd.print("Lamp 11: OFF ");
digitalWrite(led11, HIGH);
controller="Bf";
if (key=='C')
if (LC==0)
LC=1;
lcd.setCursor(0,1);
lcd.print("Lamp 12: ON ");
digitalWrite(led12, LOW);
controller="Cn";
else
LC=0;
lcd.setCursor(0,1);
lcd.print("Lamp 12: OFF ");
digitalWrite(led12, HIGH);
controller="Cf";
if (key=='D')
if (LD==0)
LD=1;
lcd.setCursor(0,1);
lcd.print("ERR: BTN D ");
controller="Dn";
else
LD=0;
lcd.setCursor(0,1);
lcd.print("ERR : BTN D ");
controller="Df";
if (key=='*')
if (LS==0)
LS=1;
lcd.setCursor(0,1);
lcd.print("Lamp ALL: ON ");
digitalWrite(led1, LOW);
digitalWrite(led2, LOW);
digitalWrite(led3, LOW);
digitalWrite(led4, LOW);
digitalWrite(led5, LOW);
189
digitalWrite(led6, LOW);
digitalWrite(led7, LOW);
digitalWrite(led8, LOW);
digitalWrite(led9, LOW);
digitalWrite(led10, LOW);
digitalWrite(led11, LOW);
digitalWrite(led12, LOW);
L1=1;
L2=1;
L3=1;
L4=1;
L5=1;
L6=1;
L7=1;
L8=1;
L9=1;
L0=1;
LA=1;
LB=1;
LC=1;
LD=1;
LH=1;
LS=1;
controller="Sn";
else
LS=0;
lcd.setCursor(0,1);
lcd.print("Lamp ALL: ON ");
digitalWrite(led1, LOW);
digitalWrite(led2, LOW);
digitalWrite(led3, LOW);
digitalWrite(led4, LOW);
digitalWrite(led5, LOW);
digitalWrite(led6, LOW);
digitalWrite(led7, LOW);
digitalWrite(led8, LOW);
digitalWrite(led9, LOW);
digitalWrite(led10, LOW);
digitalWrite(led11, LOW);
digitalWrite(led12, LOW);
L1=1;
L2=1;
L3=1;
L4=1;
L5=1;
L6=1;
L7=1;
190
L8=1;
L9=1;
L0=1;
LA=1;
LB=1;
LC=1;
LD=1;
LH=1;
LS=1;
controller="Sf";
if (key=='#')
if (LH==0)
LH=1;
lcd.setCursor(0,1);
lcd.print("Lamp ALL: OFF ");
digitalWrite(led1, HIGH);
digitalWrite(led2, HIGH);
digitalWrite(led3, HIGH);
digitalWrite(led4, HIGH);
digitalWrite(led5, HIGH);
digitalWrite(led6, HIGH);
digitalWrite(led7, HIGH);
digitalWrite(led8, HIGH);
digitalWrite(led9, HIGH);
digitalWrite(led10, HIGH);
digitalWrite(led11, HIGH);
digitalWrite(led12, HIGH);
L1=0;
L2=0;
L3=0;
L4=0;
L5=0;
L6=0;
L7=0;
L8=0;
L9=0;
L0=0;
LA=0;
LB=0;
LC=0;
LD=0;
LH=0;
LS=0;
controller="Hn";
else
LH=0;
191
lcd.setCursor(0,1);
lcd.print("Lamp ALL: OFF ");
digitalWrite(led1, HIGH);
digitalWrite(led2, HIGH);
digitalWrite(led3, HIGH);
digitalWrite(led4, HIGH);
digitalWrite(led5, HIGH);
digitalWrite(led6, HIGH);
digitalWrite(led7, HIGH);
digitalWrite(led8, HIGH);
digitalWrite(led9, HIGH);
digitalWrite(led10, HIGH);
digitalWrite(led11, HIGH);
digitalWrite(led12, HIGH);
L1=0;
L2=0;
L3=0;
L4=0;
L5=0;
L6=0;
L7=0;
L8=0;
L9=0;
L0=0;
LA=0;
LB=0;
LC=0;
LD=0;
LH=0;
LS=0;
controller="Hf";
for (int bil=0;bil<2;bil++)
digitalWrite(ledsignal,0);
vw_send((uint8_t *)controller, strlen(controller));
vw_wait_tx(); // Wait until the whole message is gone
delay(10);
digitalWrite(ledsignal,1);
192
APPENDIX M
Programming For Receiver
#include <VirtualWire.h>
int relay1 = 34;
int relay2 = 32;
int relay3 = 30;
int relay4 = 28;
int relay5 = 36;
int relay6 = 38;
int relay7 = 40;
int relay8 = 42;
int relay9 = 48;
int relay10 = 50;
int relay11 = 46;
int relay12 = 44;
int ledsignal = 2;
void setup()
Serial.begin(9600);
vw_set_ptt_inverted(true); // Required for DR3100
vw_set_rx_pin(13);
vw_setup(4000); // Bits per sec
Serial.println("rx1");
vw_rx_start(); // Start the receiver PLL running
pinMode(ledsignal, OUTPUT);
pinMode(relay1, OUTPUT);
pinMode(relay2, OUTPUT);
pinMode(relay3, OUTPUT);
pinMode(relay4, OUTPUT);
pinMode(relay5, OUTPUT);
pinMode(relay6, OUTPUT);
pinMode(relay7, OUTPUT);
pinMode(relay8, OUTPUT);
pinMode(relay9, OUTPUT);
pinMode(relay10, OUTPUT);
pinMode(relay11, OUTPUT);
pinMode(relay12, OUTPUT);
digitalWrite(relay1,1);
digitalWrite(relay2,1);
digitalWrite(relay3,1);
digitalWrite(relay4,1);
digitalWrite(relay5,1);
digitalWrite(relay6,1);
digitalWrite(relay7,1);
digitalWrite(relay8,1);
193
digitalWrite(relay9,1);
digitalWrite(relay10,1);
digitalWrite(relay11,1);
digitalWrite(relay12,1);
void loop()
uint8_t buf[VW_MAX_MESSAGE_LEN];
uint8_t buflen = VW_MAX_MESSAGE_LEN;
if (vw_get_message(buf, &buflen)) // Non-blocking
if((buf[0]=='1')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 1 0n");
digitalWrite(relay1,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='1')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
digitalWrite(relay1,1);
Serial.println("Switch 1 0ff");
digitalWrite(ledsignal,0);
if((buf[0]=='2')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 2 0n");
digitalWrite(relay2,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='2')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 2 0ff");
digitalWrite(relay2,1);
digitalWrite(ledsignal,0);
if((buf[0]=='3')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 3 0n");
digitalWrite(relay3,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='3')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 3 0ff");
digitalWrite(relay3,1);
digitalWrite(ledsignal,0);
if((buf[0]=='4')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 4 0n");
194
digitalWrite(relay4,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='4')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 4 0ff");
digitalWrite(relay4,1);
digitalWrite(ledsignal,0);
if((buf[0]=='5')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 5 0n");
digitalWrite(relay5,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='5')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 5 0ff");
digitalWrite(relay5,1);
digitalWrite(ledsignal,0);
if((buf[0]=='6')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 6 0n");
digitalWrite(relay6,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='6')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 6 0ff");
digitalWrite(relay6,1);
digitalWrite(ledsignal,0);
if((buf[0]=='7')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 7 0n");
digitalWrite(relay7,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='7')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 7 0ff");
digitalWrite(relay7,1);
digitalWrite(ledsignal,0);
if((buf[0]=='8')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 8 0n");
digitalWrite(relay8,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='8')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 8 0ff");
195
digitalWrite(relay8,1);
digitalWrite(ledsignal,0);
if((buf[0]=='9')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 9 0n");
digitalWrite(relay9,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='9')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 9 0ff");
digitalWrite(relay9,1);
digitalWrite(ledsignal,0);
if((buf[0]=='0')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch 0 0n");
digitalWrite(ledsignal,0);
else if((buf[0]=='0')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch 0 0ff");
digitalWrite(ledsignal,0);
if((buf[0]=='A')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch A 0n");
digitalWrite(relay10,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='A')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch A 0ff");
digitalWrite(relay10,1);
digitalWrite(ledsignal,0);
if((buf[0]=='B')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch B 0n");
digitalWrite(relay11,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='B')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch B 0ff");
digitalWrite(relay11,1);
digitalWrite(ledsignal,0);
if((buf[0]=='C')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
196
Serial.println("Switch C 0n");
digitalWrite(relay12,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='C')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch C 0ff");
digitalWrite(relay12,1);
digitalWrite(ledsignal,0);
if((buf[0]=='D')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch D 0n");
digitalWrite(ledsignal,0);
else if((buf[0]=='D')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch D 0ff");
digitalWrite(ledsignal,0);
if((buf[0]=='S')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch all 0n");
digitalWrite(relay1,0);
digitalWrite(relay2,0);
digitalWrite(relay3,0);
digitalWrite(relay4,0);
digitalWrite(relay5,0);
digitalWrite(relay6,0);
digitalWrite(relay7,0);
digitalWrite(relay8,0);
digitalWrite(relay9,0);
digitalWrite(relay10,0);
digitalWrite(relay11,0);
digitalWrite(relay12,0);
digitalWrite(ledsignal,0);
else if((buf[0]=='S')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch all on");
digitalWrite(relay1,0);
digitalWrite(relay2,0);
digitalWrite(relay3,0);
digitalWrite(relay4,0);
digitalWrite(relay5,0);
digitalWrite(relay6,0);
digitalWrite(relay7,0);
digitalWrite(relay8,0);
digitalWrite(relay9,0);
digitalWrite(relay10,0);
digitalWrite(relay11,0);
197
digitalWrite(relay12,0);
digitalWrite(ledsignal,0);
if((buf[0]=='H')&&(buf[1]=='n'))
digitalWrite(ledsignal,1);
Serial.println("Switch all off");
digitalWrite(relay1,1);
digitalWrite(relay2,1);
digitalWrite(relay3,1);
digitalWrite(relay4,1);
digitalWrite(relay5,1);
digitalWrite(relay6,1);
digitalWrite(relay7,1);
digitalWrite(relay8,1);
digitalWrite(relay9,1);
digitalWrite(relay10,1);
digitalWrite(relay11,1);
digitalWrite(relay12,1);
digitalWrite(ledsignal,0);
else if((buf[0]=='H')&&(buf[1]=='f'))
digitalWrite(ledsignal,1);
Serial.println("Switch all 0ff");
digitalWrite(relay1,1);
digitalWrite(relay2,1);
digitalWrite(relay3,1);
digitalWrite(relay4,1);
digitalWrite(relay5,1);
digitalWrite(relay6,1);
digitalWrite(relay7,1);
digitalWrite(relay8,1);
digitalWrite(relay9,1);
digitalWrite(relay10,1);
digitalWrite(relay11,1);
digitalWrite(relay12,1);
digitalWrite(ledsignal,0);
198
AUTHOR’S PROFILE
Hajar Ja’afar was born in Johor, Malaysia. She received B. Eng. degree in
Electrical (Electronic) from Universiti Teknologi Malaysia (UTM), Johor, Malaysia in
May 2010. In 2012, she received Msc. degree in Telecommunication and Engineering
from Universiti Teknologi Mara (UiTM), Selangor, Malaysia. She is currently
pursuing her Ph.D. degree in Electrical Engineering with the Antenna Research
Group, Microwave Technology Centre in Universiti Teknologi Mara (UiTM),
Malaysia. During her Master and PhD studies, she has been fully sponsored by the
Ministry of Higher Education and UiTM under Young Lecturer Scheme. She became
a Member (M) of IEEE in 2013 and has published several journal articles and
conference proceeding papers. Her research interest includes the area of
communication antenna design such as plasma antennas, microstrip antennas and
electromagnetic radiation analysis. She has several achievements for her Ph.D.
research designs like the Gold Medal in 2014 International Invention, Innovation,
Industrial Design and Technology (ITEX 2014), the Special Award with Gold Medal
at the International Conference and Exposition Invention of Institutions of Higher
Learning ( PENCIPTA) November 2013.
LIST OF PUBLICATIONS
A. List of Journal Articles
1. H.Ja’afar, M.T.Ali, A.N.Dagang, H.M.Zali, N.A.Halili, , “Performance
Analysis of a Monopole Antenna with Fluorescent Tubes at 4.9 GHz
Application” Innovative Systems Design and Engineering, Vol.4, No. 10,
2013.
199
2. H. Ja’afar, M.T. Ali, A.N. Dagang, H.M. Zali, N.A. Halili, "A Reconfigurable
Monopole Antenna with Fluorescent Tubes by Using Plasma Windowing
Concepts at 4.9GHz", Advanced Materials Research, Vol. 905, pp. 432-435,
Apr. 2014
3. H.Ja’afar, M.T.Ali, , A.N.Dagang, H.M.Zali, N.A.Halili, , “A Reconfigurable
Monopole Antenna with Fluorescent Tube using Windowing Concept for 4.9
GHz Application” IEEE Transaction on Plasma Science, Vol 43, No 3,March
2015.
4. H.Ja’afar, M.T. Ali, A.N. Dagang, H.M. Zali, M.Hilmi, “Analysis of
Cylindrical Monopole Plasma Antenna Behaviours by Using Discharge Tube
with Different Gases”, IEEE Antenna Wireless Propagation Letter ( Under
Review)
5. H.Ja’afar ,M.T Ali ,A.N. Dagang, N.A. Halili, H.M.Zali.,”Reconfigurable
Plasma Antenna Array by Using Fluorescent Tube for Wi-Fi Application,”
Radio Engineering (Accepted)
6. H.M.Zali, M.T.Ali, I.Pasya, N.A.Halili, H.Jaafar, M.Hilmi, “Performance of
Monopole Plasma Antenna with Cylindrical Parabolic Reflector” Pensee
Journal, Vol 76, No. 10, Oct 2014
7. N. A. Halili, M. T. Ali, I. Pasya, A. N. Dagang, H. Ja’afar, H. M. Zali, “RF
Radiation Behavior of Rare Gas in Plasma State” IOSR Journal of Electronics
and Communication Engineering, Vol 9, Pp 67-76, June 2014
B. International Conference Papers
1. H.Ja’afar, M.T. Ali, H.M.Zali, N.A Halili, A.N. “ Analysis and Design
between Plasma Antenna and Monopole Antenna” IEEE International
Symposium on Telecommunication Technologies (ISTT 2012), Kuala
Lumpur, Malaysia, 27-28 November 2012.
200
2. H.Ja’afar, M.T. Ali, H.M.Zali, N.A Halili, A.N.Dagang “A Monopole
Fluorescent Tube Antenna in Wireless Communication Application” IEEE
International Conference on Electrical Engineering / Electronics, Computer,
Telecommunications and Information Technology (ECTI-CON 2013), Krabi,
15 - 17 May 2013.
3. H.Ja’afar, M.T. Ali, A.N.Dagang, H.M.Zali, N.A Halili, , “ Design Monopole
Antenna with Fluorescent Tube at 4.9GHz” Asia-Pacific Microwave
Conference Proceedings (APMC 2013), Seoul Korea,5-8 November 2013.
4. H.Ja’afar, M.T Ali ,A.N. Dagang,N.A. Halili,H.M.Zali, “Smart Plasma
Antenna on Plasma Windowing Concept”, 8th
European Conference On
Antennas And Propagation (EuCAP 2014), The Hague, 6-11 April 2014.
5. H.Ja’afar, M.T Ali ,A.N. Dagang,N.A. Halili,H.M.Zali , “A Reconfigurable
Monopole Antenna with Fluorescent Tubes by Using Plasma Windowing
Concepts at 4.9GHz” , 3rd International Conference on Applied Materials and
Electronics Engineering (AMEE 2014), Hong Kong, 26-27 April 2014.
6. H.Ja’afar, M.T.Ali , A.N. Dagang, H.M.Zali , M.Hilmi, “Performances
Analysis of Cylindrical Monopole Plasma Antenna”, 6th
International
Confrenece on Metamaterials, Photonic Crystals and Plasmonics (META’ 15)
, New York,USA, 4-7 August 2015.
7. H.M.Zali, M.T.Ali, I.Pasya, N.ya’acob, N.A.Halili , H.Ja’afar, A.A.Azlan, “A
Monopole Fluorescent Tube Antenna With Wi-Fi Router”, 21st International
Conference on Telecommunications (ICT), Lisbon, Portugal, 5-7 May 2014.
8. H.M.Zali , M.T.Ali, N.A.Halili, H.Ja’afar, I.Pasya , “Design of a Cylindrical
Parabolic Reflector on Monopole Pla sma Antenna” IEEE International RF
and Microwave Conference (RFM 2013), Penang, Malaysia, 9-11 Dec 2013
9. H.M.Zali , M.T.Ali, N.A.Halili, H.Ja’afar, I.Pasya , “Study of Monopole
Plasma Antenna using Fluorescent Tube in Wireless Transmission
201
Experiments” IEEE International Symposium on Telecommunication
Technologies (ISTT 2012), Kuala Lumpur, Malaysia, 27-28 November 2012.
10. N.A.Halili, M.T.Ali, H.M.Zali, H.Ja’afar, I.Pasya , “A Study on Plasma
Antenna Characteristics with Different Gases” IEEE International Symposium
on Telecommunication Technologies (ISTT 2012), Kuala Lumpur, Malaysia,
27-28 November 2012.
11. N.A.Halili, M.T.Ali, H.M.Zali, H.Ja’afar, I.Pasya , A.N. Dagang“ Effects of
Coupling Sleeve Designs on an RF Charged Plasma Monopole Antenna” IEEE
International RF and Microwave Conference (RFM 2013), Penang, Malaysia,
9-11 Dec 2013.
12. K.A.C.Mat, M.T.Ali, H.Ja’afar, H.M.Zali, A.A.A Aziz “A Smart Fluorescent
Antenna with Ethernet over AC Power (EoP) for Wi-Fi Application” Asia-
Pacific Microwave Conference Proceedings (APMC 2014), Sendai, Japan, 4- 7
November 2014.
13. M.Hilmi, M.T.Ali, N. Ya’acob, H.M.Zali, H.Ja’afar, "Development of
Fluorescent Tube Antenna Array for Wi-Fi Application" 2015 IEEE
Symposium on Computer Applications & Industrial Electronics
(ISCAIE2015), Langkawi, Malaysia, 12-14 April 2015
LIST OF AWARDS/ RECOGNITIONS
1. GOLD MEDAL in Competition and Exhibition of Invention, Innovation and
Design (IID 2012) “Study of Monopole Plasma Antenna Using Fluorescent
Tube in Wireless Transmission Experiments” Science and Technology Centre,
UiTM Shah Alam.
202
2. GOLD MEDAL in Competition and Exhibition of Invention, Innovation and
Design, “Plasma Antenna Using Fluorescent Tube With 3G/3.75G/4G
Wireless and Router” (IIDEX 2013), Dewan Tuanku Canselor, UiTM Shah
Alam.
3. BRONZE MEDAL in Invention, Innovation and Design, “A Monopole
Fluorescent Tube Antenna in Wireless Communication Application” (IID
JOHOR 2013), UiTM Segamat.
4. GOLD MEDAL and SPECIAL AWARD from Korea in International
Conference and Exposition in Invention of Institution of Higher Learning, “A
Monopole Fluorescent Tube Antenna In Wi-Fi Applications” (PECIPTA
2013), KLCC, Kuala Lumpur.
5. GOLD MEDAL and INDUSTRIAL AWARD in Competition and Exhibition
Invention, Innovation and Design (IID 2013), “Fluorescent Antenna with
3G/3.75G/4G Wireless and Router” Science And Technology Centre, UiTM
Shah Alam.
6. GOLD MEDAL in International Invention, Innovation & Research Design
Platform, “Fluorescent Antenna with 3G/3.75G/4G Wireless and Router” (IP
2013), Penang
7. GOLD MEDAL in Competition and Exhibition Invention, Innovation and
Design (IIDEX 2014), “A Smart Fluorescent Antenna With EoP (Ethernet
Over Ac Power) Router For Wi-Fi Application” Dewan Tuanku Canselor,
UiTM Shah Alam.
8. GOLD MEDAL in 25th
International Invention, Innovation and Technology
Exhibition (ITEX 2014), “A Smart Fluorescent Antenna with EoP (Ethernet
over Ac Power) Router For Wi-Fi Application” KLCC Convention Centre,
Kuala Lumpur
9. SILVER MEDAL in Competition and Exhibition Invention, Innovation and
Design (IID 2014) “Development of Fluorescent Tube Array Antenna with
3G/4G Router for Wi-Fi Applications”, Science and Technology Centre,
UiTM Shah Alam.