Wideband Circularly Polarized Antenna With Gain Improvement

Abstract

A wideband circularly polarized antenna with coaxial balun feed, using a broadband 90° hybrid feed network, is proposed. By introducing a narrow patch connecting the pair of bowtie dipoles as an entity that increases the effective radiation area, the proposed antenna delivers a higher gain than that of the conventional dual-fed-type circularly polarized antenna. It can achieve a measured impedance bandwidth for VSWR ≤ 1.5 of 57% and a 3-dB axial-ratio bandwidth of 51.8%. Moreover, the antenna has stable peak circularly polarized gain better than 9.0 dBi ranging from 1.1 to 1.6 GHz. For the entire half-power beamwidth, the axial ratio can be kept below 3 dB.