A Simultaneous Study on Wire-Loop, Plate-Loop, and Plate Antennas for Wideband Circular Polarization

Abstract

We investigate three square-shaped antennas to increase the bandwidth of circular polarization. Each antenna has two adjacent corners excited with the same amplitudes and a phase difference of 90° using a branched feedline vertical to the ground plane. We evaluate the 3 dB axial ratio bandwidth as a function of the loop-arm width using the moment method. It is found that the axial ratio bandwidth reaches 38% for an arm width of 0.04 wavelengths, wider than that of a wire-loop antenna by a factor of three. The simulated results are verified by experimental ones.