Design and Implementation of a Wideband 1-Bit Transmitarray Based on a Yagi–Vivaldi Unit Cell

A novel 1-bit reconfigurable transmitarray antenna (RTA) based on a Yagi-Vivaldi unit cell for wideband and beam scanning application at the Ku-band is presented. The unit cell consists of a tightly coupled microstrip (MS) Yagi antenna and a Vivaldi antenna as the receiving and transmitting elements, respectively. To achieve a reconfigurable performance, a novel slot line to MS line phase shifter with a pair of reverse-mounted p-i-n diodes was introduced, and a 180° phase difference was achieved based on the current reversal mechanism. To improve the oblique incidence performance of the unit cell, a metasurface based on subwavelength metal crosses was loaded in front of the antenna, and the scan loss in the H-plane was improved by 2 dB. An RTA prototype with 16×16 unit cells was designed, fabricated, and tested. The measured 1 dB bandwidth of the RTA is 14% with a maximum gain of 22.3 dB at 13.6 GHz, corresponding to an aperture efficiency of 25.6%. Good beam scanning performance has also been achieved with a scan loss better than 4 dB in both the E-plane and the H-plane at 60°.