An Ultra-wideband Co-circularly-polarized Antenna for Simultaneous Transmit and Receive

An ultra-wideband, co-circularly-polarized, Archimedean-type four-arm spiral antenna with improved transmitting (Tx) to receiving (Rx) isolation for simultaneous transmit and receive (STAR) applications is presented in this paper. Together with the feeding network, the antenna can achieve high isolation level in the whole operating bandwidth. Simulated result shows the operating bandwidth covers 0.32-3 GHz, the percentage bandwidth is as wide as 161%. At the same time, Tx-Rx isolation is above 47.2 dB in the whole operating bandwidth. Meanwhile, directional RHCP radiation pattern and consistent radiation pattern between Tx and Rx antenna have been observed. Compared with similar works, the proposed antenna has the characteristics of small aperture size and novel feeding structure. These merits make the proposed antenna a candidate for STAR.