Bandwidth Enhancement of Circularly Polarized Antenna Based on Dual Layer Metasurface

In this paper, a novel single-feed circularly polarized (CP) patch antenna loaded with a spiral-rhombus-shaped metasurface layer is proposed for communication application. Based on the dual layer 5 x 5 spiral shape external converter generating linear-to-circularly polarized wave, the antenna's AR bandwidth (ARBW) has significantly enhanced. Based on the mode analysis, the CP antenna's mechanism is theoretically examined. The parameters of single feeding structure are studied to achieve wide impedance bandwidth (BW) and axial ratio (AR) BW. The simulated relative impedance bandwidth and 3 dB ARBW were 21.5 % and 8.5 %, respectively, from 3.87 GHz to 4.21 GHz. The CP antenna has a maximum gain of 6.35 dBic.