A novel probe-fed single-layer circularly polarized (CP) truncated microstrip antenna with enhanced CP bandwidth and gain is presented in this paper. The axial ratio (AR) bandwidth is broadened by loading with a circle of truncated square parasitical patches. Parameter analysis is made to investigate the effect of the loading structures on the AR property. For comparisons, both the unloaded and loaded truncated patch antennas with the same size are designed, fabricated and measured. The measurement results show that by adding the parasitical patches, the -10 dB impedance bandwidth was increased from 0.98 GHz (15.9%) to 1.42 GHz (21.5%), among which the 3-dB RHCP AR bandwidth has been increased from 200 MHz (3.3% at the center frequency of 6.04 GHz) to 780 MHz (12.6% at the center frequency of 6.19 GHz). The gain enhancement is about 0.5 dB~1.5 dB around the operating frequency range, and the maximum gain of the proposed antenna is about 9.1 dB. With the advantages of simple structure, wide CP bandwidth and considerable gain property, this antenna has potential application in wireless communications.
2. Carver, K. R. and J. R. Mink, "Microstrip antenna technology," IEEE Trans. Antennas Propag., Vol. 29, No. 1, 2-24, Jan. 1981.
3. Sharma, P. C. and K. C. Gupta, "Analysis and optimized design of single feed circularly polarized microstrip antennas," IEEE Trans. Antennas Propag., Vol. 31, No. 6, 949-955, Nov. 1983.
4. Tong, K. F. and T. P.Wong, "Circularly polarized U-slot antenna," IEEE Trans. Antennas Propag., Vol. 55, No. 8, 2382-2385, Aug. 2007.
5. Khidre, A., K. F. Lee, F. Yang, and A. Eisherbeni, "Wideband circularly polarized E-shaped patch antenna for wireless applications," IEEE Antennas Propag. Mag., Vol. 52, No. 5, 219-229, Oct. 2010.
6. Nasimuddin, Z. N. Chen, and X. M. 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.
7. Wang, C. and K. Chang, "Single-layer wideband probe-fed circularly polarized microstrip antenna," Proc. IEEE Antennas Propag. Soc. Int. Symp. Dig., 1000-1003, Salt Lake City, UT, 2000.
8. Egashira, S. and E. Nishiyama, "Stacked microstrip antenna with wide bandwidth and high gain," IEEE Trans. Antennas Propag., Vol. 44, No. 11, 1533-1534, Nov. 1996.
9. Herscovici, N., Z. Sipus, and D. Bonefacic, "Circularly polarized single fed wideband microstrip patch," IEEE Trans. Antennas Propag., Vol. 51, No. 6, 1277-1280, Jun. 2003.
10. Nasimuddin, K. P. Esselle, and A. K. Verma, "Wideband circularly polarized stacked microstrip antennas," IEEE Antennas and Wireless Propag. Lett., Vol. 6, 21-24, 2007.
11. Lo, W. K., J. L. Hu, C. H. Chan, and K. M. Luk, "Circularly polarized patch antenna with an L-shaped probe fed by a microstrip line," Microw. Opt. Technol. Lett., Vol. 24, 412-414, 2000.
12. Nasimuddin, K. P. Esselle, and A. K. Verma, "Wideband high-gain circularly polarized stacked microstrip antennas with an optimized C-type feed and a short horn," IEEE Trans. Antennas Propag., Vol. 56, No. 2, 578-581, Feb. 2008.
13. Cao, W. Q., B. N. Zhang, T. B. Yu, and H. B. Li, "A single-feed broadband circular polarized rectangular microstrip antenna with chip-resistor loading," IEEE Antennas and Wireless Propag. Lett., Vol. 9, 1065-1068, 2010.
14. Wong, K. L. and T. W. Chiou, "Broad-band single-patch circularly polarized microstrip antenna with dual capacitively coupled feeds," IEEE Trans. Antennas Propag., Vol. 49, No. 1, 41-44, Jan. 2001.
15. Karmakar, N. C. and M. E. Bialkowski, "Circularly polarized aperture coupled circular microstrip patch antennas for L-band applications," IEEE Trans. Antennas Propag., Vol. 47, No. 5, 933-940, May 1999.
16. Tang, X. H., Y. L. Long, H. Wong, K. L. Lau, and , "Broadband circularly-polarised patch antenna with 3D meandering strip feed," Electron. Lett., Vol. 47, No. 19, 1060-1062, 2011.
17. Lin, Q. W., H. Wong, X. Y. Zhang, and H. W. Lai, "Printed meandering probe-fed circularly polarized patch antenna with wide bandwidth," IEEE Antennas and Wireless Propag. Lett., Vol. 13, 654-657, 2014.
18. Cao, W. Q. and W. Hong, "Bandwidth and gain enhancement for single-fed compact microstrip antenna by loading with parasitical patches," ICMMT2016, Beijing, 2016.
19. Luther, J. J., S. Ebadi, and X. Gong, "A microstrip patch electronically steerable parasitic array radiator (ESPAR) antenna with reactance-tuned coupling and maintained resonance," IEEE Trans. Antennas Propag., Vol. 60, No. 4, 1803-1813, Apr. 2012.
20. Yang, X. M., X. G. Liu, X. Y. Zhou, and T. J. Cui, "Reduction of mutual coupling between closely packed patch antennas using wave guided metamaterials," IEEE Antennas Wireless Propag. Lett., Vol. 11, 389-391, Apr. 2012.
21. Farsi, S., H. Aliakbarian, D. Schreurs, B. Nauwelaers, and G. A. E. Vandenbosch, "Mutual coupling reduction between planar antennas by using a simple microstrip U-section," IEEE Antennas Wireless Propag. Lett., Vol. 11, 1501-1503, Dec. 2012.