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Improved performance of Microstrip Antenna Arrays through Electromagnetic
Coupling(EMCP) at Ka-band
Pratigya Mathur and Girish Kumar
Antenna Lab, Electrical Engineering Department,
IIT Bombay, India
pratigya.mathur@gmail.com, pmathur@iitb.ac.in
gkumar@ee.iitb.ac.in
Forum for Electromagnetic Research Methods and Application Technologies
(FERMAT)
Copyright
The use of this work is restricted solely foracademic purposes. The author of this work ownsthe copyright and no reproduction in any form ispermitted without written permission by theauthor.
Indian Institute Of Technology Bombay, India 2
Abstract
Corporate fed Microstrip Antenna Array (MSAA) and Electromagnetically
Coupled Microstrip Antenna Array (EMCP-MSAA) : A comparison
Based on the analysis of different microstriplines of varying line widths, a
low loss feed network is proposed.
Gain improvement of 25% (1.5 dB) is achieved using the proposed feed
network in 2×2 EMCP-MSAA.
8×8 MSAA - designed and fabricated at Ka-band. Measured Bandwidth:
4.3% and Gain: 24dB.
Bandwidth enhancement done by designing and fabricating EMCP-MSAA.
Bandwidth:17% for 8×8 array.
Keywords: Antenna array, Bandwidth, Electromagnetically Coupled (EMCP), High Gain, Microstrip.
Indian Institute Of Technology Bombay, India 3
Biography
Girish Kumar is a professor at Indian Institute of Technology
Bombay and has 30 years of experience in designing
antennas and microwave circuits. He has published more
than 290 papers in the national and international journals and
conference proceedings. He has written two books and filed
for 6 patents.
Pratigya Mathur is currently pursuing Ph.D. at Indian
Institute of Technology Bombay. Her research interests are
RF, Microwaves, Microstrip Antennas and Arrays. She has
been working on various project in collaboration with Indian
Space Research Organization (ISRO) and Defence
Research and Development Organisation (DRDO).
Indian Institute Of Technology Bombay, India 4
Presentation Outlines
Introduction
Analysis of Single Patch and Electromagnetically Coupled (EMCP) Antennas
Design of Corporate feed Microstrip Antenna Array at Ka-band and its Measured Results
Design of Low-Loss Feed Network
Design of Broadband EMCP Antenna Array and its Measured Results
Conclusions
Indian Institute Of Technology Bombay, India 5
Introduction
• Millimeter-Waves Applications are of increasing interestbecause of the wide bandwidth available and small size.
• Wide bandwidth supports high speed data transmissionand video distribution.
• High gain antennas are required to overcomeatmospheric attenuation due to absorption of microwaveenergy by water vapors or molecular oxygen in longrange communication systems.
• High gain Microstrip Antenna Array and BroadbandEMCP antenna arrays have been designed.
Indian Institute Of Technology Bombay, India 6
Analysis of Single Patch and EMCP Antennas
Substrate para: εr=2.2, h=0.254mm, tan δ = 0.001
Patch antenna with its Top and Side view
Indian Institute Of Technology Bombay, India 7
Patch
Substrate
GND
SMA Connector
2.64mm
2.8
mm
Patch1Substrate
SMA Connector2h+
0.5
mm
Patch2
2.26mm
2.59mm
3.2
mm
EMCP antenna with its Top and Side view
0.4mm0.9 mm
Edge impedance for single patch at 35.5GHz is approximately 200 Ω and for EMCP
patch is nearly 50 Ω.
Analysis of Single Patch and EMCP Antennas
EMCP Antenna gives larger bandwidth from 33-42GHz (24%) and Patch
antenna gives bandwidth from 34.3-36GHz (2.4%)
EMCP Antenna gives larger gain of 8.8dB over its bandwidth and Patch
antenna gives gain of 7dB
Indian Institute Of Technology Bombay, India 8
Design of Microstrip Antenna Array
Microstrip lines of 0.44mm (70.7 Ω)
and 0.22mm (100 Ω ) are used. W2,
W3, W4 and W6 are 0.44mm (70.7 Ω).
W5 and W7 are 0.22mm (100 Ω).
• Substrate para: εr=2.2, h=0.254mm, tan δ = 0.001
• Patch length 2.6mm and width 2.8mm
• Distance between the patches is taken as 5.8mm (0.697λo)
Indian Institute Of Technology Bombay, India 9
Patch & feed network
SubstrateGND
SMA Connector
Results of Microstrip Antenna Array
Array SizeFreq
(GHz)
Gain
(dB)
Bandwidth
(GHz)
2×2 35.7 12.7 35.3-36.2(2.5%)
4×4 35.3 18.4 34.8-35.8(2.8%)
8×8 35.75 24.2 34.8-35.8(2.8%)
As the size of the antenna array increases, gain increases and bandwidth also increases.
Indian Institute Of Technology Bombay, India 10
Measured Results of 8x8 MSA Array
Indian Institute Of Technology Bombay, India 11
5cm5cm
Fabricated 8×8 MSAA Measured bandwidth (S11<-10dB) :
33.6-35.3GHz (4.3%)
SLL better than -13dB
Atenuation vs Frequency of ….
Indian Institute Of Technology Bombay, India 12
Gain of the antenna is
improved by using low loss
feed lines at Ka-band
50 Ω line becomes more lossy
at Ka-band than a frequency
below 10GHz
Order of losses at higher
frequency:
50 Ω > 70.7 Ω > 100Ω
Width of the lines of feed
network must be chosen
depending upon frequency of
operation to reduce losses to
improve the antenna gain.
Design of Low Loss Feed Network for MSAA
Indian Institute Of Technology Bombay, India 13
Low Loss
Feed
Network
Gain improvement of >1.5 dB using the low loss network in 2×2 EMCP-MSAA
Design of EMCP Antenna Array
Indian Institute Of Technology Bombay, India 14
Array SizeGain
(dB)
Bandwidth
(GHz)
2×2 13.6 32.3-40 (19.9%)
4×4 18.7 32.9-39.3(17.7%)
8×8 24.2 33.6-39.4(15.8%)
.
• Bandwidth of the antenna increases
due to electromagnetic coupling of
the patches
• As the size of the antenna array
increases, gain increases but
bandwidth decreases slightly
Results of 8x8 EMCP Antenna Array
Indian Institute Of Technology Bombay, India 15
6.5cm
Measured BW: 32-38GHz (17%)
SLL better than -13dB
Gain of 25dB
Simulated BW: 33.6- 39.4GHz (15.8%)
Conclusions
EMCP Antenna Array technique gives broadbandwidth and high gain.
It has been analyzed that order of losses in microstriplines at higher frequency is as follows:
50 Ω > 70.7 Ω > 100Ω
Gain improvement of 1.5 dB using the low loss network in achieved in 2×2 EMCP-MSAA
Due to low loss feed network EMCP antenna arraygives gain of at least 25 dB.
With lossy feed network the gain would have beeneven lower than Microstrip Antenna Array.
Indian Institute Of Technology Bombay, India 16
References
1. G. Kumar and K. P. Ray Broadband Microstrip Antenna, Artech House, USA 2003.
2. R. Garg, P. Bhartia, I. Bahl, and A. Ittipiboon, Microstrip Antenna Design Handbook. Boston, MA: Artech House, 2000.
3. Yiwei Wu; Qi Zhu, "Design of a Ka-band microstrip antenna array with sharped-beam pattern and high gain," Antennas and Propagation Society International Symposium (APSURSI), 2013 IEEE , pp.1582-1583, 7-13 July 2013
4. Sabban, A., "Ka band microstrip antenna arrays with high efficiency," Antennas and Propagation Society International Symposium, 1999. IEEE , vol.4, pp.2740- 2743 vol.4, 11-16 July 1999
5. Aixin Chen; et. al, "A -Band High-Gain Circularly Polarized Microstrip Antenna Array," Antennas and WirelessPropagation Letters, IEEE , vol.9, pp.1115,1118, 2010
6. Yi-Chun Lilia Liu; Yuanxun Ethan Wang, "A 16×16 ka band aperture-coupled microstrip planar array," Antennasand Propagation Society International Symposium, 2007 IEEE , pp.4373,4376, 9-15 June 2007
7. Huang, J., "A Ka-band circularly polarized high-gain microstrip array antenna," IEEE Transactions on Antennasand Propagation, vol.43, no.1, pp.113,116, Jan 1995
8. Wolansky, D.; Vsetula, P.; Puskely, J.; Raida, Z., "Broadband small patch antenna array for Ka-band application," ,2013 7th European Conference on Antennas and Propagation (EuCAP), pp.907- 910, 8-12 April 2013
9. Wilke, R.; et.al., "Multi-layer patch antenna array design for Ka-band satellite communication," Microwave &Optoelectronics Conference (IMOC), 2013 SBMO/IEEE MTT-S International ,pp.1,4, 4-7 Aug. 2013.
10. Mentor Graphics Corp., IE3D EM Design System, Ver. 15.0, Wilsonville, USA, 2010.
Indian Institute Of Technology Bombay, India 17
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