A 50 OHM MICROSTRIP LINE FED SHORTED HEXAGONAL MICROSTRIP ANTENNAS WITH REDUCED CROSS-POLARIZATION

Authors

  • S. M. Rathod
  • R. N. Awale
  • K. P. Ray

DOI:

https://doi.org/10.1590/2179-10742019v18i21436

Keywords:

Cross-polarization, Fundamental mode, Inset feed, Edge fed hexagonal antenna, Shorting post

Abstract

A Hexagonal Microstrip Antenna (HMSA) is an approximation to a Circular MSA (CMSA), which is not symmetrical over two principal planes, unlike a CMSA. Consequently, two types of feed positions are feasible for each X and Y-axes. When a feeding technique like a quarter-wave transformer or inset fed is used to match the edge impedance, the HMSA structure becomes asymmetrical over the feed axis ( E-plane), which leads to increase in the cross-polar level in the H-plane. In this paper, to reduce the cross-polarisation level of HMSA along H-plane, a method of loading shorting posts into the patch have been used. To match the edge impedance of the HMSA on each X and Y-axes with the 50- Ohm Microstrip (MS)-line-fed, initially a single shorting post has been used. Later on, a pair of shorting post is used along both the axes of HMSA for operation at around 2.4 GHz. The current distribution of the shorted HMSA has been changed due to the loading of shorting posts into the patch, which in-turns help to match the edge input impedance. Therefore, without changing the patch geometry, a wide extent of impedance matching can be realised. A detailed investigation on the characteristics of the shorted HMSA with modified fundamental mode frequencies has been presented. The co-polarization to cross-polarization ratios (CTCR) in H-plane of the HMSA with a pair of shorting posts has been reduced substantially with more than 20 dB at the broadsight direction in comparison with that of an HMSA with a single shorting post or with an inset. The simulated results of the HMSA with direct 50 Ohm-MS-line-feed are in good agreement with measured ones.

References

[1] Kin-Lu Wong, Compact and Broadband Microstrip Antennas, John Wiley & Sons, Inc., New York, USA, 2002.
[2] G. Kumar and K. P. Ray, Broadband Microstrip Antennas, Norwood, MA, Artech House, USA, 2003.
[3] C. A. Balanis, Antenna Theory: Analysis and Design, Third Edition, New York, John Wiley and Sons, Inc., 2005.
[4] L. I. Basilio, M. A. Khayat, J. T. Williams, and S. A. Long, “The Dependence of the Input Impedance on Feed Position
of Probe and Microstrip Line-Fed Patch Antennas,” IEEE Trans. Antennas and Propag., vol. 49, no. 1, pp. 45-47, Jan.
2001.
[5] Y. Hu, D. R. Jackson, J. T. Williams, S. A. Long, and V. R. Komanduri, “Characterization of the Input Impedance of the
Inset-fed Rectangular Microstrip Antenna,” IEEE Trans. Antennas and Propag., vol. 56, no. 10, pp. 3314-3318, Oct.
2008.
[6] D. Schaubert, F. Farrar, A. Sindoris and S. Hayes, “Microstrip Antennas with Frequency Agility and Polarization
Diversity,” IEEE Trans. Antennas and Propag., vol. 29, no. 1, 118-123, Jan 1981.
[7] K. P. Ray, “Broadband, Dual Frequency and Compact Microstrip Antennas”, PhD thesis, Indian Institute of Technology,
Bombay, India, 1999.
[8] S. Bhardwaj and Y Rahmat-Samii, “Revisiting the Generation of Cross Polarization in Rectangular Patch Antennas: A
Near-Field Approach”, IEEE Antennas and Propag. Mag, vol. 56, no. 1, pp. 14-38, Feb 2014.
[9] J. S. Row, “A Simple Impedance-Matching Technique for Patch Antennas Fed by Coplanar Microstrip Line,” IEEE
Trans. Antennas and Propag., vol. 53, no. 10, pp. 3389-3391, Oct 2005.
[10] X. Zhang and L. Zhu, “Patch Antennas with Loading of a Pair of Shorting Pins Toward Flexible Impedance Matching
and Low Cross-Polarization,” IEEE Trans. Antennas and Propag., vol. 64, no. 4, pp. 1226-1233, 2016.
[11] S. M. Rathod, R. N. Awale and K. P. Ray, "Analysis of a single shorted rectangular microstrip antenna for 50Ω microstrip
line feed," 2016 International Symposium on Antennas and Propagation (APSYM), Cochin,2016, pp. 1-4.
[12] S. M. Rathod, R. N. Awale, and K. P. Ray, “Shorted Circular Microstrip Antennas for 50 Ω Microstrip Line Feed with
Very Low Cross-Polarization,” Progress In Electromagnetics Research Letters, vol. 74, pp.91-98, 2018.
[13] A. Chapari, A. Zeidaabadi Nezhad and Z. H. Firouzeh, “Analytical Approach for Compact Shorting Pin Circular Patch
Antenna,” IET Microwaves Antennas Propag., vol. 11, no. 11, pp.1603-1608, 2017.
[14] A. A. Deshmukh, S. Pawar, P. Kadam, A. Odhekar and K. P. Ray, “Analysis of single shorted square microstrip
antenna,” 2017 International Conference on Emerging Trends & Innovation in ICT (ICEI), Pune, 2017, pp. 123-128.
[15] S. Samanta, P. S. Reddy and K. Mandal, “Cross-Polarization Suppression in Probe-Fed Circular Patch Antenna Using
Two Circular Clusters of Shorting Pins,” IEEE Trans. Antennas and Propag., vol. 66, no. 6, pp. 3177-3182, June 2018.
[16] N. Liu, L. Zhu, G. Fu and Y. Liu, “A Low Profile Shorted-Patch Antenna With Enhanced Bandwidth and Reduced HPlane Cross-Polarization,” IEEE Trans. Antennas and Propag., vol. 66, no. 10, pp. 5602-5607, Oct. 2018.
[17] K. P. Ray and M. D. Pandey, “Resonance Frequency of Hexagonal and Half-hexagonal Microstrip Antennas,” Microw.
Opt. Technol. Lett., vol. 51, no. 2, pp. 448–452, 2009.
[18] HyperLynx 3D EM Design System, Mentor Graphics Corp, Ver. 15.2, Wilsonville, USA, 2012.

Downloads

Published

2020-04-10

How to Cite

S. M. Rathod, R. N. Awale, & K. P. Ray. (2020). A 50 OHM MICROSTRIP LINE FED SHORTED HEXAGONAL MICROSTRIP ANTENNAS WITH REDUCED CROSS-POLARIZATION. Journal of Microwaves, Optoelectronics and Electromagnetic Applications (JMOe), 18(2), 246-262. https://doi.org/10.1590/2179-10742019v18i21436

Issue

Section

Regular Papers