1. Zeng, D. Z. and Q. X. Chu, "Cavity-backed self-phased circularly polarized multidipole antenna with wide axial-ratio beamwidth," IEEE Antennas Wireless Propag. Lett., Vol. 16, 1998-2001, 2017.
doi:10.1109/LAWP.2017.2692769
2. Wang, S. Y., X. Zhang, L. Zhu, and W. Wu, "Single-fed wide-beamwidth circularly polarized patch antenna using dual-function 3-D printed substrate," IEEE Antennas Wireless Propag. Lett., Vol. 17, No. 4, 649-653, Apr. 2018.
doi:10.1109/LAWP.2018.2810105
3. Luo, Y., Q. X. Chu, and L. Zhu, "A low-profile wide-beamwidth circularly-polarized antenna via two pairs of parallel dipoles in a square contour," IEEE Trans. Antennas Propag., Vol. 63, No. 3, 931-936, Mar. 2015.
doi:10.1109/TAP.2014.2387438
4. Bai, X., J. Tang, X. Liang, J. Geng, and R. Jin, "Compact design of triple band circularly polarized quadrifilar helix antennas," IEEE Antennas Wireless Propag. Lett., Vol. 13, 380-383, 2014.
5. Yang, Y.-H., J.-L. Guo, B.-H. Sun, and Y.-H. Huang, "Dual-band slot helix antenna for global positioning satellite applications," IEEE Trans. Antennas Propag., Vol. 64, No. 12, 5146-5152, Dec. 2016.
doi:10.1109/TAP.2016.2623647
6. Choi, E. C., J. W. Lee, and T. K. Lee, "Modified S-band satellite antenna with isoflux pattern and circularly polarized wide beamwidth," IEEE Antennas Wireless Propag. Lett., Vol. 12, 1319-1322, 2013.
doi:10.1109/LAWP.2013.2285231
7. Tang, C. L., J. Y. Chiou, and K. L. Wong, "Beamwidth enhancement of a circularly polarized microstrip antenna mounted on a three-dimensional ground structure," Microw. Opt. Technol. Lett., Vol. 32, No. 2, 149-153, Jan. 2002.
doi:10.1002/mop.10116
8. Su, C. W., S. K. Huang, and C. H. Lee, "CP microstrip antenna with wide beamwidth for GPS band application," Electron. Lett., Vol. 43, No. 20, 1062-1063, Sep. 2007.
doi:10.1049/el:20071691
9. Bao, X. L. and M. J. Ammann, "A cavity-backed spiral slot antenna with wide axial ratio beamwidth for GPS system," Microw. Opt. Technol. Lett., Vol. 56, No. 5, 1050-1054, May 2014.
doi:10.1002/mop.28255
10. Son, H. W., H. Park, K. H. Lee, G. J. Jin, and M. K. Oh, "UHF RFID reader antenna with a wide beamwidth and high return loss," IEEE Trans. Antennas Propag., Vol. 60, No. 10, 4928-4932, Oct. 2012.
doi:10.1109/TAP.2012.2207349
11. Wang, M. S., X. Q. Zhu, Y. X. Guo, and W. Wu, "Compact circularly polarized patch antenna with wide axial-ratio beamwidth," IEEE Antennas Wireless Propag. Lett., Vol. 17, 714-718, Apr. 2018.
doi:10.1109/LAWP.2018.2813160
12. Liu, N. W., L. Zhu, and W. W. Choi, "Low-profile wide-beamwidth circularly-polarised patch antenna on a suspended substrate," IET Microw. Antennas Propag., Vol. 10, No. 8, 885-890, May 2016.
doi:10.1049/iet-map.2016.0081
13. 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
14. Zhang, X., L. Zhu, N. W. Liu, and D. P. Xie, "Pin-loaded circularly-polarized patch antenna with sharpened gain roll-off rate and widened 3-dB axial ratio beamwidth," IET Microw. Antennas Propag., Vol. 12, No. 8, 1247-1254, 2018.
doi:10.1049/iet-map.2017.0970
15. Sun, C., H. L. Zheng, and Y. Liu, "Compact dual-band circularly polarized GNSS antenna," Electron. Lett., Vol. 51, No. 20, 1559-1560, Oct. 2015.
doi:10.1049/el.2015.1920
16. Chen, K., J. D. Yuan, and X. Y. Luo, "Compact dual-band dual circularly polarized annular-ring patch antenna for BeiDou navigation satellite system application," IET Microw. Antennas Propag., Vol. 11, No. 8, 1079-1085, May 2017.
doi:10.1049/iet-map.2016.1057
17. Zhang, Y. Q., X. Li, L. Yang, and S. X. Gong, "Dual-band circularly polarized annular-ring microstrip antenna for GNSS applications," IEEE Antennas Wireless Propag. Lett., Vol. 12, 615-618, May 2013.
doi:10.1109/LAWP.2013.2260521
18. Liu, Q., Y. Li, Z. G. Mo, and Y. A. Liu, "Compact broadband circularly-polarised directional universal GNSS antenna with symmetric radiation pattern and stable near zenith coverage," IET Microw. Antennas Propag., Vol. 11, No. 5, 657-663, 2017.
doi:10.1049/iet-map.2016.0815
19. Bao, X. L. and M. J. Ammann, "Dual-frequency dual circularly-polarised patch antenna with wide beamwidth," Electron. Lett, Vol. 44, No. 21, 1233-1234, Oct. 2008.
doi:10.1049/el:20082284
20. Ta, S. X., I. Park, and R. W. Ziolkowski, "Dual-band wide-beam crossed asymmetric dipole antenna for GPS applications," Electron. Lett., Vol. 48, No. 25, 1580-1581, Dec. 2012.
doi:10.1049/el.2012.2890
21. Sun, Y. X., K. W. Leung, and J. Ren, "Dual-band circularly polarized antenna with wide axial ratio beamwidths for upper hemispherical coverage," IEEE Access, Vol. 6, 58132-58138, Oct. 2018.
22. Shie, C. I., J. C. Cheng, S. C. Chou, and Y. C. Chiang, "Trans-directional coupled-line couplers implemented by periodical shunt capacitors," IEEE Trans. Microw. Theory Techn., Vol. 57, No. 12, 2981-2988, Dec. 2009.
doi:10.1109/TMTT.2009.2034219
23. Liu, H., S. Fang, Z. Wang, and T. Shao, "Coupled line trans-directional coupler with improved power distribution and phase performance," 2017 IEEE International Symposium on Radio- Frequency Integration Technology (RFIT), 126-128, Seoul, 2017.
24. Rezazadeh, N. and L. Shafai, "Study of finite ground plane effects in circularly polarized circular microstrip antennas," 2016 17th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM), 2016, DOI: 10.1109/ANTEM.2016.7550228.