A Wideband Monostatic Co-Circularly Polarized Simultaneous Transmit and Receive Antenna Using Metasurface

A wideband mono static metasurface-based simultaneous transmit and receive (STAR) antenna system with high isolation and co-circularly polarized (Co-CP) radiation is proposed. The STAR antenna consists of a
$2\times 2$
dual-polarized metasurface (DPMS) antenna array shared by TX and RX for mono static operation. To achieve high TXlRX isolation and identical right-handed CP (RHCP), the four TX and RX ports of the STAR antenna are excited with equal amplitudes and relative phases of 0°, 90°, 180°, and 270°, respectively, by using two wideband integrated feeding networks. Measured results show that the proposed STAR antenna system achieves
$> 36\text{dB}$
TXlRX isolation and
$< 3\text{dB}$
axial ratio from 4.5 to 6 GHz, and maintains similar radiation patterns with the same RHCP for TX and RX.