Improving the axial-ratio bandwidth of circularly polarized stacked microstrip antennas and enhancing their gain with short horns

A systematic technique is developed to improve the AR bandwidth of circularly polarized stacked microstrip antennas (CPSMAs) to about 14% by optimizing the location of the feed and a few other parameters. A new C-type single feed is explored for this purposes. Then a CPSMA is integrated with a quasi-planar short horn to enhance its gain. Our results indicate that it is possible to increase the gain by 4.5 dB without compromising the 3 dB axial ratio (AR) bandwidth or the 10 dB return loss bandwidth of the CPSMA. The final design has a gain of 11.5 dBi, 3 dB AR bandwidth of 15.2%, minimum AR of 0.27 dB and a 10 dB return loss bandwidth of 21.5%. The proposed techniques simplify the design of wideband circularly polarized antennas for medium to high gain applications