Wideband circularly polarised slot antenna

A wideband circularly polarised slot antenna is presented. The slot antenna is fed by four microstrip line feeds orientated to have relative phases of 0deg, 90deg, 180deg and 270deg using a feed network comprising a pair of broadband 90deg 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.