Wideband circularly polarised slot antenna

Abstract

A wideband circularly polarised slot antenna is presented. The slot antenna is fed by four microstrip line feeds orientated to have relative phases of 0°, 90°, 180° and 270° using a feed network comprising a pair of broadband 90° hybrid. The proposed antenna delivers measured and simulated impedance bandwidths of 77.8% (1.02–2.32 GHz) and 89.1% (1.02–2.66 GHz), respectively, for standing wave ratio (SWR)<2, measured and simulated axial-ratio bandwidths of 88.9% (1–2.6 GHz) and 81% (1.1–2.6 GHz), respectively, for axial ratio < 3 dB and measured and simulated gain bandwidths of 33% (1.5–2.1 GHz) and 27% (1.6–2.1 GHz), respectively, for gain >3 dB. A good agreement is observed between simulation and measurement.