A Beam Steerable Resonant Cavity Antenna Based on Tunable Partially Reflective Surface

A beam steerable resonant cavity antenna (RCA) enabled by using tunable partially reflective surface (PRS) is proposed in this paper. Tunable PRS loaded with varactor diodes evolves from complementary frequency selective surface (FSS) which consists of square loop patch and slot arrays. The reflection phase of PRS unit cell can be tuned by adjusting the biasing status of varctors, while the reflection magnitude keep a relative high value within a frequency band of interest, owing to the complementary configuration. The reflection coefficients of PRS unit cells are independently controlled in rows so that a gradient phase distribution within the aperture can be achieved, leading to an ID scannable directive beam. An implementation is demonstrated with simulated results, which exhibits maximum scanned angle of 13 degrees with a gain of 13.6 dB for a $2\lambda\times 2\lambda$ antenna aperture size.