Wide-band circularly polarized cavity backed crossed dipole antenna

Abstract

In this paper, a wide-band circularly polarized (CP) crossed dipole antenna is proposed. The CP crossed dipole antenna is backed by a cavity reflector to achieve wide-band CP radiation with enhanced gain and uni-directional pattern accompanied by high front to back lobe ratio. A comprehensive study on the effect of the vertical walls of the cavity reflector on the CP radiation performance has been performed. It is analyzed that the cavity reflector provides an additional CP mode which is merged with the reference CP mode of crossed dipole to get a bandwidth enhancement in the CP operation. The concentration of electric field vectors on the inner walls of cavity provides an enhanced and stable gain of a CP crossed dipole across the entire CP operating bandwidth as compared to a PEC reflector backed crossed dipole antenna. The concept of wide-band, uni-directional and high gain CP crossed dipole antenna is validated by measurement carried out on the fabricated antenna prototype. Measured results confirm that the cavity backed crossed dipole exhibits a CP operating bandwidth of 22.89% (2.52–3.17 GHz), an average gain of 8 dBic and uni-directional radiation pattern with a front to back lobe ratio > 25 dB.