Advances In Microwave Engineering 

Dr. Kushal R. TuckleyChairman and Director R&D AGV systems

Kushal_tuckley@rediffmail.com

What Do We Mean By Microwave?

• Common Man: Microwave oven!

• Radio frequency used in TV Satellite link

• The Radio Frequency Used by Radars

• Some range of Radio Frequency

So we quickly look into the spectrum

RF and Microwave Spectrum

Applications of Microwaves• Communication : Space, Terrestrial• Broadcasting : Satellite TV• Navigation :GPS• Remote sensing : Earth and Astronomical Study• Radars : Strategic, Atmospheric• Dielectric Heating : Cooking, Disinfection• Instrumentation :Sensors, Detectors, Security• Spectroscopy : Chemical Measurements • Linear Accelerator : Medical and X-ray Imaging

Clear Air Atmospheric Radars: Working Principle

Indian MST RADARThe Indian Mesospheric Stratospheric & Tropospheric radar (MST) was designed developed and commissioned by SAMEER at Gadanki near

Tirupati in Andhra Pradesh Location: 13.4o N, 79.17 oE

Wind Profiler RASS IMD, Pune

Wind profiler Antenna

Doppler Weather Radar

IONOSPHEREThe  ionosphere  is the partially  ionized region of the atmosphere. It  is present at heights of about 60 km to 450 Km. It  is  divided  into  different  layers  or  regions;  D,  E,  F1  and  F2. These  regions correspond to different altitude, composition and electron density levels. In  the  nighttime,  there  is  no  solar  radiation  to  produce  ionization,  so recombination makes the D, E and F1 layers disappear. Typical daytime and nighttime profiles are shown in the figure.The F2  layer does not disappear at  sunset,  instead  its density  slowly decreases throughout the night.

Ionosonde for Earthquake Prediction?!

Antenna for vertical Ionospheric Sounding

Antenna’s  for  vertical Ionospheric Sounding  are crucial  element  in  the general  design.  The Following  things  are  crucial for Tx and Rx antenna’s”The  Tx and  Rx  antenna’s have  to  be wide  band  due to  the  wide  frequency range.The  main  radiation  lobe needs  to  be  directed towards the zenith.

Ionosonde Transmit Antenna

Conventional Transmit Antenna

baluns

Co‐ax feed line to Tx & Rx

mast24m

Termination box

Insulated support,Two on each arm

Double Delta Transmit Antenna

Receive Antenna

Magnetic  loop  turnstile antenna 

Arranged  in  orthogonal planes

Provides  polarization  of the received radiation

Antenna  elements  are arranged  in  4  or  7 antenna patterns.

Configuration of Receive antennas

functional block Diagram of Ionosonde

PCI BUS

ADC

POLARIZATIONSWITCH

TX/RX SWITCH

BPF

LNA

POLARISATION SWITCH

TX/RX SWITCH

BPF

LNA

POLARISATION SWITCH

TX/RX SWITCH

BPF

LNA

POLARISATION SWITCH

TX/RX SWITCH

BPF

LNA

ADC ADC ADC

DDC DDC

FPGA

PCI BUS PCI BUS

FPGA

PCI BUS

POWER AMPLIFIER

BPF

SYNTHESIZER & CODE GENERATOR

REFERENCE CLOCK GENERATOR

SWITCH

Transmitter Receiver

The Ionogram studies

The Echoes from Ionosphere are Obtained by sweeping the Frequency 1MHz to 20MHzNormal Echoes are circularly polarized as the transmit wave. They indicate the layer boundaries. Whereas the extraordinary echoes are  a circularly polarised in other direction.

IonosondeThese are HF radars for Ioniospheric Studies

Facilities in India

Over The Horizon Radar (SkyWave)These HF radars use Ionosphere as a mirror to detect the targets.They offer very large range and hence of strategically great importance

Working Principle

OTH Radar Working Principle

OTH Coverage USA

OTH Sea Wave Transmit Antenna Array

Bangor ANGB, ME,USA

Relocatable OTH Radar station(N/TPS‐71 ROTHR, Receiver array)

OTH (sea-wave) Radar1. Vertically Polarised EM wave 

Propagates  along  the  sea surface beyond the horizon 

2. Detection  of  targets  up  to 300 Km is possible   

HF antenna Array

Propagating Wave

Sea Surface

Earth

Relocatable OTH Radar station(US Navy)

Sea Monitoring Radars

Motivation 

Operating Principle

Orthogonal Antennas for Direction Finding

Transmit antenna Receive Antenna

Antenna Pattern of Cross-polar Dipoles

BASEBANDAMP.

LPF

The spectrum analysis and oceanographic interpretation system

DIGITAL CONTROL

UNIT

SYSTEM CLOCK

OSCILLATOR

PC

CONTROL SIGNALS

HARMONIC FILTER

DDS

POWER AMP

SWITCHING CIRCUIT

TRANSMITTER ANTENNA

DC DC CONVERTOR to all the blocks

LIMITER FILTER

LNASWITCH

AGC AMP

RECEIVER ANTENNA

LIMITER FILTER

LNASWITCH

LNASWITCH

LIMITER FILTER

AGC AMP

AGC AMP

MIXER

ANALOG TO DIGITAL

CONVERSION

BLOCK DIAGRAM of SEA SONDE:

BASEBANDAMP.

LPF

BASEBANDAMP.

LPFMIXER

MIXER

DIGITALPROCESSOR & FPGA

Typical Doppler Spectrum of Seasonde

Spectrum ‘X’ channel Spectrum ‘Y’ Channel

SeaSonde Data Presentation

Single Seasonde

Combination of Two Seasonde

Coastal Ocean Dynamic Application Radars(Locations in the US)

C-Band TT&C Transponder – Receiver Bottom Deck-Microwave Subsystems 2

C-Band TT&C Transponder – Receiver Middle DeckDeck-Microwave Subsystems-1

Linear Accelerator for Cancer Treatment

Internal Structure of LINAC Arm

LINAC Structure

Internal Field Distribution

Linear particle Acceleration by Microwaves

Internal Structure of a Cavity

6 MeV Stack (Brazed)

4 & 15 MeV Linac

Magnetic Resonance Imaging

Processing for MRI Pictures

External Magnetic Field (B)(Increasing Magnitude)

Frequency Sweep RF Pulsed Transceiver

(Radar Principle)

Resonant Frequency Response of 

Specific  Tissues is Proportional to the Magnetic 

Field

MRI Pictures

Research Areas in Microwave Engineering(Numerical method of Computation)

• Efficient methods for numerical computation of electromagnetic scattering and antenna radiation.

• FDTD (Finite Difference Time Domain) software development.

• Radar cross section design for wide band applications

• Planar Near‐field Antenna Measurements

• Microwave Holography

• Planar antennas and arrays, e.g. for automotive radar • Ultra‐wide‐band antennas• Integrated antennas and lenses• Electromagnetic Interference suppression• Planar Near‐field Antenna Measurements• Efficiency in the use of power, spectrum utilization, ability to integrate and being compatible with other technologies

• Phase Retrieval for antenna metrology. Terahertz near‐field measurements

• Fractal Antennas

Research Areas in Microwave EngineeringAntenna Design and Measurements

Research Areas in Microwave Engineeringcomponents and systems

• Photonic Band Gap filters and antennas

• Active Antenna arrays

• Microwave cavity design for high Power application

• Adaptive Array design 

• Transmit‐Receive module for radars

• Wide Band Phase shifters

• Disinfection using microwaves

• Frequency agile wide band transmitter

• Microwave assisted chemical reactions

• Effects of microwave radiation on plants and animals

Thank You All !!