Loop antennas with wideband circular polarization

Abstract

Using the method of moments, we analyze three types of loop antennas with a perturbation segment (PS). Each loop has a single feed and is backed by a ground plane. It is found that the first loop having double PS's shows a circularly polarized (CP) wave bandwidth of 5% for a 3-dB axial-ratio criterion, which is two times wider than that of the second loop having a single PS. Further analysis reveals that a CP wave bandwidth of 9% can be obtained for the third loop having a single PS whose length is greatly increased.