Wideband Beam Steering Using a 4-Arm Spiral Array for Simultaneous Transmit and Receive (STAR) Operation

We demonstrate a wideband scanning 4-arm spiral antenna array with high transmit/receive isolation for Simultaneous Transmit and Receive (STAR). STAR increases a channel's spectral efficiency by transmitting and receiving across the full bandwidth of a channel. To our knowledge, this is the first STAR array to demonstrate scanning across GHz bandwidths. Each 4-arm spiral element is divided into two arms for transmit and two more for receive. To suppress grating lobes, the element spacing is kept at less than λ/2. A 3×3 array prototype was fabricated and measurements agree well with simulations.