A Broadband Circularly Polarized Patch Antenna With Improved Axial Ratio

In this letter, a novel method to improve the axial ratio (AR) of circularly polarized patch antenna is presented. The feed network consists of a broadband balun and two L-shaped probes. By introducing a metal sheet between the probes, the AR could be improved at the upper sideband significantly, where there exhibits a downward tendency. Therefore, a wider bandwidth of the AR can be achieved. The proposed antenna shows a measured impedance (|S₁₁| <; 10 dB) and 3-dB AR bandwidths of 62.3% and 61.7%, respectively. The measured bandwidth for gain 3> dBi is 40.3%.