A 1-Bit Reconfigurable Transmitarray With Enhanced Cross-Polarization Discrimination

A wideband 1-bit reconfigurable transmitarray (RTA) with low cross-polarization and 2-D beam-scanning capacity is proposed for X-band applications. Based on the patch antenna, an RTA element was designed with symmetrical on the top and bottom layers, each capable of 1-bit phase control. Slots placed on the patch structure impede cross-polarization currents, improving cross-polarization discrimination (XPD) by over 10 dB compared to unslotted designs. To further suppress the cross-polarization radiation level, a dual-layer phase coding scheme is proposed. It improves XPD by carefully selecting RTA element states and configuring the phase distribution for cross-polarization symmetric cancellation, achieving an average improvement of more than 5 dB across different beam scanning angles. Owing to the symmetry of the RTA element, the proposed RTA can be fed from either the top or bottom, improving XPD in both directions. An RTA consisting of a 15 × 15-element configuration and fed by a patch antenna is designed and fabricated to demonstrate the proposed scheme. The RTA exhibits a peak gain of 18.5 dBi at 9.5 GHz and demonstrates effective ±60° scanning coverage in both principal planes, achieving an XPD of 40 dB at the scanning angle of 0°.