This paper proposes low profile, high gain and wideband circularly polarized (CP) microstrip antennas (MSA), using gap coupled parasitic patches (PPs) on superstrate layer. Printed and suspended probe fed, CP MSAs are designed on a 1.59 mm thick FR4 substrate, and an array of closely spaced hexagonal PPs are printed on the bottom side of the 1.59 mm thick FR4 superstrate and placed at a height about λ0/8, above the ground plane, where λ0 is the free space wavelength, corresponding to the central frequency of the operating frequency band. The gap coupled hexagonal PPs are not only used to enhance the axial ratio bandwidth (AR BW) and gain of the antenna, but also used to reduce impedance and gain variation of the antenna over the operating frequency band. `Ant9' is a suspended MSA with 7 hexagonal PPs. A prototype `Ant9' is fabricated and tested, which provides a peak gain of 9 dBi, S11 < -10 dB, gain variation < 1 dB, and AR < 3 dB over 4.9 to 6.45 GHz frequency band. ARBW of 27.3% is achieved. The proposed `Ant9' covers three frequency bands viz., 5.15 to 5.35 GHz, WLAN band, 5.725 to 5.875 GHz, ISM band, and 5.9 to 6.4 GHz, Satellite C band. The space fed antenna configuration reduces the cross polar radiation level (CPL) and increases the efficiency of the antenna. A prototype antenna is fabricated and tested. The measured results agree with the simulation ones. The overall size of `Ant9' is 0.96λ0×0.96λ0×0.136λ0.
2. Oraizi, H. and R. Pazoki, "Wideband circularly polarized aperture-fed rotated stacked fed antenna," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 3, 1048-1054, 2013.
3. Yang, W., J.-Y. Zhou, Z. Yu, and L. Li, "Single fed low profile broadband circularly polarized stacked patch antenna," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 10, 5406-5410, Oct. 2014.
4. Yang, W., W.-J. Sun, W. Qin, J.-X. Chen, and J.-Y. Zhou, "Broadband circularly polarized stacked patch antenna with integrated dual feed network," IET Microwave and Antennas Propagation, Vol. 11, No. 12, 1791-1795, 2017.
5. Nasimuddin, X. Qing, and Z. N. Chen, "A wideband circularly polarized stacked slotted microstrip patch antenna," IEEE Antennas and Propagation Magazine, Vol. 55, No. 6, Dec. 2013.
6. Kumar, G. and K. P. Ray, Broadband Microstrip Antennas, Artech House, Norwood, MA, 2003.
7. Deshmukh, A. A., A. Parvez, P. Verma, A. Desai, P. Kadam, and K. P. Ray, "Space fed ring microstrip antenna array with stacked rectangular microstrip antenna feed," IEEE Annual India Conference (INDICON), 2017, ISSN: 2325-9418.
8. Mathur, P. and G. Kumar, "Non radiating edge coupled rectangular microstrip antenna array," IEEE Asia-Pacific Microwave Conference, 2017, ISSN: 2165-4743.
9. Kumar, H. and G. Kumar, "Compact planar Yagi-Uda antenna with improved characteristics," 11th Euro-pean Conference, 2017.
10. Hao, Y., G. Wang, Y. Tian, Y. Wang, L. Yu, and X. Ye, "Wide beamwidth circularly polarized microstrip Yagi array antenna," IEEE International Confrenece on Communication Problem-Solving (ICCP), Apr. 2016.
11. Li, Y., S. Sun, and F. Yang, "Miniaturized Yagi-Uda-oriented double-ring antenna with circular polarization and directional pattern," IEEE Antennas and Wireless Propag. Lett., Vol. 12, 945-948, 2013.
12. Zhou, W., J. Liu, and Y. Long, "A broadband and high-gain planar complementary Yagi array antenna with circular polarization," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 3, 1446-1451, Jan. 2017.
13. Vaidya, A. R., R. K. Gupta, S. K. Mishra, and J. Mukherjee, "Right-hand/left-hand circularly polarized high-gain antennas using partially reflective surfaces," IEEE Antennas and Wireless Propag. Lett., Vol. 13, 431-434, 2014.
14. Ji, L.-Y., P.-Y. Qin, and Y. Jay Guo, "Wideband Fabry-Perot cavity antenna with a shaped ground plane," IEEE Access, Vol. 6, 2291-2297, 2018.
15. Wang, N., J. Li, G. Wei, L. Talbi, Q. Zeng, and J. Xu, "Wideband Fabry-Perot resonator antenna with two layers of dielectric superstrates," IEEE Antennas Wireless and Propag. Lett., Vol. 14, 229-232, 2015.
16. Samanta, G. and S. R. Bhadra Choudhuri, "Design of a compact CP antenna with enhanced bandwidth using a novel hexagonal ring based reactive impedance substrate," Progress In Electromagnetics Research M, Vol. 69, 115-125, 2018.