volume | PIER Journals

Abstract

This paper presents the configurations of U-slot cut hexagonal microstrip antennas loaded with shorting posts, which realize a reduction in the center frequency of axial ratio bandwidth as well as the total substrate thickness. Three configurations employing four, eight, and twelve shorting posts positioned around a hexagonal patch are presented. Shorting posts loading adds to the inductive component in the antenna's input impedance, which yields a reduction in total substrate thickness and frequency. Among three variations, the U-slot cut hexagonal patch employing eight shorting posts yields the optimum result. It achieves axial ratio bandwidth of 2.23%, for 0.033λ_cAR reduction in the substrate thickness and 55 MHz (4.5%) reduction in the center frequency of axial ratio bandwidth. All these results are for marginal reduction in peak broadside gain. Against the U-slot cut hexagonal patch on a reduced substrate thickness, shorting posts loaded antenna achieves higher axial ratio bandwidth with 56 MHz (4.81%) reduction in the center frequency of axial ratio bandwidth. Considering all these results, the proposed design offers a compact circular polarized solution, while employing a resonant U-slot. For the obtained antenna characteristics, the proposed designs can find applications in GPS L5 and L2 bands. Experimental validation for the proposed configurations has been carried out where the measured results show close agreement with simulated ones.

1. Balanis, C. A., Antenna Theory: Analysis and Design, John Wiley & Sons, 1996.

2. Kumar, Girish and K. P. Ray, Broadband Microstrip Antennas, Artech House, 2003.

3. Garg, Ramesh, Microstrip Antenna Design Handbook, Artech House, 2001.

4. Guha, Debatosh and Yahia M. M. Antar, Microstrip and Printed Antennas: New Trends, Techniques and Applications, John Wiley & Sons, 2011.

5. Almalki, Mazen, Bandar Alshammari, and Symon K. Podilchak, "Dual-circularly polarized single-element patch antenna with compact multiport feeding," IEEE Antennas and Wireless Propagation Letters, Vol. 23, No. 2, 648-652, 2024.
doi:10.1109/lawp.2023.3331577 Google Scholar

6. Ray, Mrityunjoy Kumar, Kaushik Mandal, and Nasimuddin Nasimuddin, "Low-profile circularly polarized patch antenna with wide 3 dB beamwidth," IEEE Antennas and Wireless Propagation Letters, Vol. 18, No. 12, 2473-2477, 2019.
doi:10.1109/lawp.2019.2940703 Google Scholar

7. Zhao, Zhipeng, Feng Liu, Jian Ren, Ying Liu, and Yingzeng Yin, "Dual-sense circularly polarized antenna with a dual-coupled line," IEEE Antennas and Wireless Propagation Letters, Vol. 19, No. 8, 1415-1419, 2020.
doi:10.1109/lawp.2020.3003943 Google Scholar

8. Agrawal, Niraj, Anil K. Gautam, and Rajesh Mishra, "Design of low volume circularly polarized annular ring‐shaped planar antenna for GPS applications," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 31, No. 7, e22698, 2021.
doi:10.1002/mmce.22698 Google Scholar

9. Shi, Yuzhong and Juhua Liu, "A circularly polarized octagon-star-shaped microstrip patch antenna with conical radiation pattern," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 4, 2073-2078, 2018.
doi:10.1109/tap.2018.2800801 Google Scholar

10. Wu, Qiong-Sen, Xiao-Yu Tang, Xiao Zhang, Lei Zhu, Gary Zhang, and Chun-Bing Guo, "Circularly-polarized patch antennas with enhanced bandwidth based on capacitively coupled orthogonal patch radiators," IEEE Open Journal of Antennas and Propagation, Vol. 4, 472-483, Apr. 2023.
doi:10.1109/ojap.2023.3270939 Google Scholar

11. Wang, Zhen, Heng Luo, Jian Dong, Meng Wang, Jinchao Tong, Chengwang Xiao, Jinfei Zheng, and Rigeng Wu, "Wearable broadband circularly polarized antenna with characteristic mode analysis for wireless body area network applications," IEEE Antennas and Wireless Propagation Letters, Vol. 24, No. 6, 1312-1316, 2025.
doi:10.1109/lawp.2025.3534273 Google Scholar

12. Verma, Anamika, Mahima Arrawatia, and Girish Kumar, "High gain wideband circularly polarized microstrip antenna array," IEEE Transactions on Antennas and Propagation, Vol. 70, No. 11, 11183-11187, 2022.
doi:10.1109/tap.2022.3209191 Google Scholar

13. Li, Meiling, Junjie Yu, Xiaopeng Shen, Lebsework Negash Lemma, Dan Zeng, and Zixuan Yi, "Compact broadband GNSS antenna with wide AR beamwidth," IEEE Antennas and Wireless Propagation Letters, Vol. 24, No. 10, 3301-3305, 2025.
doi:10.1109/lawp.2025.3587304 Google Scholar

14. Lee, Kai Fong, Kwai Man Luk, Wing Chi Mok, and Payam Nayeri, "Single probe-fed circularly polarized patch antennas with U-slots," Microwave and Optical Technology Letters, Vol. 53, No. 6, 1245-1253, 2011.
doi:10.1002/mop.26012 Google Scholar

15. Chen, Yikai and Chao-Fu Wang, "Characteristic-mode-based improvement of circularly polarized U-slot and E-shaped patch antennas," IEEE Antennas and Wireless Propagation Letters, Vol. 11, 1474-1477, 2012.
doi:10.1109/lawp.2012.2231046 Google Scholar

16. Mondal, Tapas, Sandip Maity, Rowdra Ghatak, and Sekhar Ranjan Bhadra Chaudhuri, "Design and analysis of a wideband circularly polarised perturbed psi-shaped antenna," IET Microwaves, Antennas & Propagation, Vol. 12, No. 9, 1582-1586, 2018.
doi:10.1049/iet-map.2017.0569 Google Scholar

17. Zeng, Jianping, Xiuye Liang, Lianxing He, Fang Guan, Feng Han Lin, and Jian Zi, "Single-fed triple-mode wideband circularly polarized microstrip antennas using characteristic mode analysis," IEEE Transactions on Antennas and Propagation, Vol. 70, No. 2, 846-855, Feb. 2022.
doi:10.1109/tap.2021.3111280 Google Scholar

18. Rahmat-Samii, Yahya and Joshua M. Kovitz, "Wideband E-shaped patch antennas for advanced wireless terminals," Advanced Electromagnetics, Vol. 12, No. 2, 1-19, 2023.
doi:10.7716/aem.v12i2.2191 Google Scholar

19. Deshmukh, Amit A. and Tejal P. Page, "Unequal length U-slot cut design of polygon shape microstrip antenna for dual band response," International Journal of Microwave & Optical Technology, Vol. 18, No. 2, 153, 2023. Google Scholar

20. Kumar, Yatendra, Ravi Kumar Gangwar, and Binod Kumar Kanaujia, "Compact broadband circularly polarized Hook‐shaped microstrip antenna with DGS plane," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 28, No. 6, e21275, 2018.
doi:10.1002/mmce.21275 Google Scholar

21. Wei, K., J. Y. Li, L. Wang, R. Xu, and Z. J. Xing, "A new technique to design circularly polarized microstrip antenna by fractal defected ground structure," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 7, 3721-3725, 2017.
doi:10.1109/tap.2017.2700226 Google Scholar

22. Khajevandi, Amir and Homayoon Oraizi, "Design of a circularly polarized microstrip slot antenna using Minkowski fractal by the characteristic mode theory," Electronics Letters, Vol. 58, No. 9, 352-355, 2022.
doi:10.1049/ell2.12466 Google Scholar

23. Nguyen-Trong, Nghia, Leonard Hall, and Christophe Fumeaux, "A frequency-and polarization-reconfigurable stub-loaded microstrip patch antenna," IEEE Transactions on Antennas and Propagation, Vol. 63, No. 11, 5235-5240, 2015.
doi:10.1109/tap.2015.2477846 Google Scholar

24. Ta, Son Xuat, Khac Kiem Nguyen, Chien Dao-Ngoc, Nghia Nguyen-Trong, et al. "Single-layer, dual-band, circularly polarized, proximity-fed meshed patch antenna," IEEE Access, Vol. 10, 94560-94567, 2022.
doi:10.1109/access.2022.3204685 Google Scholar

25. Deshmukh, Amit A., Aniruddh Viswanathan, Prasanna Nadkarni, Venkata A. P. Chavali, and Heet Mistry, "Reconfigurable designs of equilateral triangular microstrip antennas for single and dual band circular polarized response in GSM and GPS applications," AEU --- International Journal of Electronics and Communications, Vol. 193, 155729, Mar. 2025.
doi:10.1016/j.aeue.2025.155729 Google Scholar

26. Liang, Zhuo-Xian, De-Cao Yang, Xing-Chang Wei, and Er-Ping Li, "Dual-band dual circularly polarized microstrip antenna with two eccentric rings and an arc-shaped conducting strip," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 834-837, 2016.
doi:10.1109/lawp.2015.2476505 Google Scholar

27. Dong, Hongwei, Yu Xiao, Shuting Tan, Jun Hu, and Zengping Chen, "Dual-broadband circularly polarized reconfigurable antenna based on asymmetric U-slot patch," IEEE Antennas and Wireless Propagation Letters, Vol. 22, No. 12, 3052-3056, 2023.
doi:10.1109/lawp.2023.3309504 Google Scholar

28. Chen, Wen-Wei, Qiong-Sen Wu, and Xiao Zhang, "Unified design of dual-band and triband dual-sense circularly polarized patch antennas under quad-mode operation," IEEE Antennas and Wireless Propagation Letters, Vol. 24, No. 6, 1332-1336, 2025.
doi:10.1109/lawp.2025.3535583 Google Scholar

29. Zhang, Xiao, Lei Zhu, and Neng-Wu Liu, "Pin-loaded circularly-polarized patch antennas with wide 3-dB axial ratio beamwidth," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 2, 521-528, 2017.
doi:10.1109/tap.2016.2632728 Google Scholar

30. Deshmukh, Amit A., A. P. C. Venkata, Aarti G. Ambekar, and Tushar Sawant, "Analysis of multiple shorting posts loaded square microstrip antenna for circular polarized response," Proceedings of International Conference on Wireless Communication, 207-214, Springer, Singapore, 2022.
doi:10.1007/978-981-16-6601-8_19

31. CST Software, Version 2019.

32. Chavali, Venkata A. P. and Amit A. Deshmukh, "Wideband designs of regular shape microstrip antennas using modified ground plane," Progress In Electromagnetics Research C, Vol. 117, 203-219, 2021.
doi:10.2528/pierc21110202 Google Scholar

33. Toh, B. Y., R. Cahill, and V. F. Fusco, "Understanding and measuring circular polarization," IEEE Transactions on Education, Vol. 46, No. 3, 313-318, Aug. 2003.
doi:10.1109/te.2003.813519 Google Scholar

34. Deshmukh, Amit A., Jugal Manek, and Aarti G. Ambekar, "Circularly polarized variations of truncated corner square microstrip antennas employing a U-slot," IETE Journal of Research, Vol. 71, No. 2, 554-565, 2025.
doi:10.1080/03772063.2024.2426698 Google Scholar

35. Deshmukh, Amit A. and Venkata A. P. Chavali, "Reconfigurable designs of U-slot cut microstrip antennas for dual band circularly polarized response," Progress In Electromagnetics Research B, Vol. 116, 1-18, 2026.
doi:10.2528/pierb25072205 Google Scholar

Professor Amit A. Deshmukh

Dr. Sujay Tawde

Dr. Sanjay B. Deshmukh