Improved performance of Microstrip Antenna Arrays through Electromagnetic Coupling(EMCP) at Ka-band

Transcription

1 Forum for Electromagnetic Research Methods and Application Technologies (FERMAT) 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

2 Copyright The use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author. Indian Institute Of Technology Bombay, India 2

3 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

4 Biography 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). 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. Indian Institute Of Technology Bombay, India 4

5 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

6 Introduction Millimeter-Waves Applications are of increasing interest because of the wide bandwidth available and small size. Wide bandwidth supports high speed data transmission and video distribution. High gain antennas are required to overcome atmospheric attenuation due to absorption of microwave energy by water vapors or molecular oxygen in long range communication systems. High gain Microstrip Antenna Array and Broadband EMCP antenna arrays have been designed. Indian Institute Of Technology Bombay, India 6

7 2.8mm Analysis of Single Patch and EMCP Antennas 2h+0.5mm 3.2mm Substrate para: εr=2.2, h=0.254mm, tan δ = mm 2.59mm 0.4mm 0.9 mm Patch 2.26mm GND SMA Connector Substrate Patch1 SMA Connector Patch2 Substrate Patch antenna with its Top and Side view EMCP antenna with its Top and Side view Edge impedance for single patch at 35.5GHz is approximately 200 Ω and for EMCP patch is nearly 50 Ω. Indian Institute Of Technology Bombay, India 7

8 Analysis of Single Patch and EMCP Antennas EMCP Antenna gives larger bandwidth from 33-42GHz (24%) and Patch antenna gives bandwidth from GHz (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

9 Design of Microstrip Antenna Array Substrate para: εr=2.2, h=0.254mm, tan δ = Patch length 2.6mm and width 2.8mm Distance between the patches is taken as 5.8mm (0.697λo) GND SMA Connector Patch & feed network Substrate 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). Indian Institute Of Technology Bombay, India 9

10 Results of Microstrip Antenna Array Array Size Freq (GHz) Gain (db) Bandwidth (GHz) (2.5%) (2.8%) (2.8%) As the size of the antenna array increases, gain increases and bandwidth also increases. Indian Institute Of Technology Bombay, India 10

11 Measured Results of 8x8 MSA Array 5cm Fabricated 8 8 MSAA Measured bandwidth (S11<-10dB) : GHz (4.3%) SLL better than -13dB Indian Institute Of Technology Bombay, India 11

12 Atenuation vs Frequency of. 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. Indian Institute Of Technology Bombay, India 12

13 Design of Low Loss Feed Network for MSAA Low Loss Feed Network Gain improvement of >1.5 db using the low loss network in 2 2 EMCP-MSAA Indian Institute Of Technology Bombay, India 13

14 Design of EMCP Antenna Array Array Size Gain (db) Bandwidth (GHz) (19.9%) (17.7%) (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. Indian Institute Of Technology Bombay, India 14

15 Results of 8x8 EMCP Antenna Array 6.5cm Measured BW: 32-38GHz (17%) Simulated BW: GHz (15.8%) Gain of 25dB SLL better than -13dB Indian Institute Of Technology Bombay, India 15

16 Conclusions EMCP Antenna Array technique gives broad bandwidth 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 array gives gain of at least 25 db. With lossy feed network the gain would have been even lower than Microstrip Antenna Array. Indian Institute Of Technology Bombay, India 16

17 References 1. G. Kumar and K. P. Ray Broadband Microstrip Antenna, Artech House, USA R. Garg, P. Bhartia, I. Bahl, and A. Ittipiboon, Microstrip Antenna Design Handbook. Boston, MA: Artech House, 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 , 7-13 July Sabban, A., "Ka band microstrip antenna arrays with high efficiency," Antennas and Propagation Society International Symposium, IEEE, vol.4, pp vol.4, July Aixin Chen; et. al, "A -Band High-Gain Circularly Polarized Microstrip Antenna Array," Antennas and Wireless Propagation Letters, IEEE, vol.9, pp.1115,1118, Yi-Chun Lilia Liu; Yuanxun Ethan Wang, "A ka band aperture-coupled microstrip planar array," Antennas and Propagation Society International Symposium, 2007 IEEE, pp.4373,4376, 9-15 June Huang, J., "A Ka-band circularly polarized high-gain microstrip array antenna," IEEE Transactions on Antennas and Propagation, vol.43, no.1, pp.113,116, Jan Wolansky, D.; Vsetula, P.; Puskely, J.; Raida, Z., "Broadband small patch antenna array for Ka-band application,", th European Conference on Antennas and Propagation (EuCAP), pp , 8-12April 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 Mentor Graphics Corp., IE3D EM Design System, Ver. 15.0, Wilsonville, USA, Indian Institute Of Technology Bombay, India 17