A Dual-Layer Reconfigurable Transmitarray Antenna Based on Two Orthogonal Modes

A novel 1-bit dual-layer reconfigurable transmitarray antenna (RTA) based on two orthogonal modes is presented in this letter. In contrast to traditional multilayer designs, the proposed element has a compact structure with only two metallic layers printed on opposite sides of a single dielectric substrate. The upper and lower patches of the element form a cavity-like structure with two orthogonal modes. An L-shaped slot is loaded on the upper patch to make the structure asymmetric and the two orthogonal modes in the cavity can be converted to each other, realizing the polarization rotation. To realize a reconfigurable structure, a pair of PIN diodes are placed at both ends of the π-shaped slot (combined by an L-shaped slot and a reverse L-shaped slot) to change the direction of the mode rotation clockwise or counterclockwise. The bias network for controlling the PIN diodes is also integrated into the two metallic layers. An RTA prototype with 16 × 16 elements is designed, fabricated, and measured. The measured 3 dB bandwidth of the RTA is 21.2% from 3.8 to 4.7 GHz, with a realized gain of 18.2 dBi at 4 GHz. Good beam scanning performance has also been achieved in the E- and H-planes.