Wideband circularly polarized antenna with backside plates

In this study, a novel circularly-polarized microstrip antenna fed by microstrip line to excite wideband and circularly polarized (CP) radiation is proposed. The CP antenna consists of a tapered slot and a delay line phase shifter. The proposed antenna excited wideband return loss better than 10 dB from 4.18 to 7.57 GHz, possessing the 3 dB axial ratio bandwidth from 4.25 to 6.75 GHz, and the measured antenna gain is about 9 to 10.5 dBic with the broadside radiation pattern.