A compact broadband circularly-polarized (CP) patch antenna with a wide 3-dB axial-ratio (AR) beamwidth is proposed for universal ultra-high-frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna consists of four triangular radiation patches and a compact feed network. Each of the radiation patches is grounded by shorting pins for 3-dB AR beamwidth enhancement and patch miniaturization. The feed network having a miniaturized hybrid coupler and two trans-directional couplers is proposed for good circular polarization. Measured results show that the -10-dB impedance bandwidth of the antenna is 18.4% (820-986 MHz); the 2.5-dB AR bandwidth is 32.8% (700-975 MHz); and the gain is 5.12 dBic. The measured 3-dB AR beamwidths for the planes of phi = 0° and phi = 45° are 177° and 190°, respectively. The overall antenna size is 0.408λ0 × 0.408λ0 × 0.053λ0 at 900 MHz.
"A Compact Broadband Circularly-Polarized Patch Antenna with Wide Axial-Ratio Beamwidth for Universal UHF RFID Applications," Progress In Electromagnetics Research C,
Vol. 113, 1-11, 2021. doi:10.2528/PIERC21032704
1. Trinh, L.-H., K.-T. Lu, M.-T. Nguyen, N.-V. Truong, and F. Ferrero, "Miniature circularly polarized antenna for UHF RFID handheld reader: design and experiments," Progress In Electromagnetics Research M, Vol. 93, 43-52, 2020. doi:10.2528/PIERM20041004
2. Wang, Z., S. Fang, S. Fu, and S. Jia, "Single-fed broadband circularly polarized stacked patch antenna with horizontally meandered strip for universal UHF RFID applications," IEEE Trans. Microwave Theory Tech., Vol. 59, No. 4, 1066-1073, Apr. 2011. doi:10.1109/TMTT.2011.2114010
3. Wang, P., G. Wen, J. Li, Y. Huang, L. Yang, and Q. Zhang, "Wideband circularly polarized UHF RFID reader antenna with high gain and wide axial ratio beamwidths," Progress In Electromagnetics Research, Vol. 129, 365-385, 2012. doi:10.2528/PIER12042501
4. Nasimuddin, Z. N. Chen and X. Qing, "Asymmetric-circular shaped slotted microstrip antennas for circular polarization and RFID applications," IEEE Trans. Antennas Propag., Vol. 58, No. 12, 3821-3828, Dec. 2010. doi:10.1109/TAP.2010.2078476
5. Sim, C.-Y.-D., C. Lin, T. Chen, J. Liou, and H. Chou, "An eccentric annular slotted patch with parasitic element for UHF RFID reader applications," IEEE Int. Conf. RFID Technology and Applications, 37-40, Pisa, Italy, 2019.
6. Sim, C.-Y.-D., Y.-W. Hsu, and G. Yang, "lits loaded circularly polarized universal UHF RFID reader antenna," IEEE Antennas Wireless Propag. Lett., Vol. 14, 827-830, 2015. doi:10.1109/LAWP.2014.2382557
7. Li, J., H. Liu, S. Zhang, M. Luo, Y. Zhang, and S. He, "A wideband single-fed, circularly-polarized patch antenna with enhanced axial ratio bandwidth for UHF RFID reader applications," IEEE Access, Vol. 6, 55883-55892, 2018. doi:10.1109/ACCESS.2018.2872692
8. Pan, Y. M., W. J. Yang, S. Y. Zheng, and P. F. Hu, "Design of wideband circularly polarized antenna using coupled rotated vertical metallic plates," IEEE Trans. Antennas Propag., Vol. 66, No. 1, 42-49, Jan. 2018. doi:10.1109/TAP.2017.2769690
9. Nasimuddin, X. Qing and Z. N. Chen, "A wideband circularly polarized stacked slotted microstrip patch antenna," IEEE Antennas Propag. Mag., Vol. 55, No. 6, 84-99, Dec. 2013. doi:10.1109/MAP.2013.6781708
10. Chen, X., G. Fu, S.-X. Gong, Y.-L. Yan, and W. Zhao, "Circularly polarized stacked annular-ring microstrip antenna with integrated feeding network for UHF RFID readers," IEEE Antennas Wireless Propag. Lett., Vol. 9, 542-545, 2010. doi:10.1109/LAWP.2010.2051791
11. Chung, H. L., X. Qing, and Z. N. Chen, "A broadband circularly polarized stacked probe-fed patch antenna for UHF RFID applications," Int. J. Antennas Propag., Vol. 2007, Art. ID 76793, 8 pages, 2007.
12. Kwa, H. W., X. Qing, and Z. N. Chen, "Broadband single-fed single-patch circularly polarized antenna for UHF RFID applications," IEEE AP-S Int. Symp., 1-4, San Diego, USA, 2008.
13. Chen, Z. N., X. Qing, and H. L. Chung, "A universal UHF RFID reader antenna," IEEE Trans. Microwave Theory Tech., Vol. 57, No. 5, 1275-1282, May 2009. doi:10.1109/TMTT.2009.2017290
14. Wu, S., J. Yuan, J. Chen, and Y. Li, "Compact circularly polarized microstrip ring antenna using capacitive coupling structure for RFID readers," IEEE Access, Vol. 8, 32617-32623, 2020. doi:10.1109/ACCESS.2020.2973719
15. Huang, G.-L., C.-Y.-D. Sim, C.-W. Lin, and M.-J. Gao, "Low-profile UHF RFID reader antenna with CP radiation and coupled feeding technique," Int. J. RF Microw. Comput. Aided Eng., Vol. 26, No. 9, 819-828, 2016. doi:10.1002/mmce.21034
17. Xu, H.-X., G.-M. Wang, and M.-Q. Qi, "A miniaturized triple-band metamaterial antenna with radiation pattern selectivity and polarization diversity," Progress In Electromagnetics Research, Vol. 137, 275-292, 2013. doi:10.2528/PIER12081008
18. Xu, H.-X., G.-M. Wang, M. Q. Qi, T. Cai, and T. J. Cui, "Compact dual-band circular polarizer using twisted Hilbert-shaped chiral metamaterial," Opt. Express, Vol. 21, No. 21, 24912-24921, Oct. 2013. doi:10.1364/OE.21.024912
19. Ng, K.-B., C. H. Chan, and K. M. Luk, "Low-cost vertical patch antenna with wide axial-ratio beamwidth for handheld satellite communications terminals," IEEE Trans. Antennas Propag., Vol. 63, No. 4, 1417-1424, Apr. 2015. doi:10.1109/TAP.2015.2403314
20. Zhang, X., L. Zhu, and N.-W. Liu, "Pin-loaded circularly-polarized patch antennas with wide 3-dB axial ratio beamwidth," IEEE Trans. Antennas Propag., Vol. 65, No. 2, 521-528, Feb. 2017. doi:10.1109/TAP.2016.2632728
22. Liu, H., S. Fang, Z. Wang, and T. Shao, "Coupled line trans-directional coupler with improved power distribution and phase performance," IEEE Int. Symp. Radio-Frequency Integration Technology, 126-128, Seoul, Korea, 2017.
23. Mandal, M. K. and S. Sanyal, "Reduced-length rat-race couplers," IEEE Trans. Microwave Theory Tech., Vol. 55, No. 12, 2593-2598, Dec. 2007. doi:10.1109/TMTT.2007.910058
24. Pozar, D. M., Microwave Engineering, 4th Edition, John Wiley & Sons, New York, 2012.