A Simplified, Double-Layer and Low-Profile 1-Bit Reconfigurable Reflectarray for 2-D Space-Time Beam Steering

This letter presents a simplified, double-layer, and low-profile 1-bit reconfigurable reflectarray (RRA). To keep the 1-bit performance of the element on a single substrate, the point with the numerically weakest electric field is selected as the location of the biasing point without using additional radio frequency choke components. An L-shaped slot is cut in the ground plane to guide the biasing line, and square slots are cut to reserve enough area to route the lines of each element. A 12 × 12 RRA prototype is fabricated and tested to validate its 2-D space-time beam-steering capability. For spatial beams, the experimental results indicate a 2-D beam scanning of ±50° and a maximum aperture efficiency of 15.7%. For spatiotemporal beams, we propose and verify a space-time coding strategy in case of phase delay introduced by the horn feed. The thickness of RRA is only 1.524 mm (1/40λ at 5.0 GHz). The proposed design can be a low-cost candidate for supporting RRA applications.