Design of Compact Beam-Steering Antennas Using a Metasurface Formed by Uniform Square Rings

Abstract

In this paper, we propose two designs of slot-fed metasurface antenna for beam steering applications. Both designs have the same two-layer stacked configuration consisting of either a single-slot or a double-slot radiator and a metasurface superstrate. In contrast to existing phase-gradient metasurfaces with varying unit elements for beam steering, our proposed metasurface is formed by uniform square rings. At operating frequencies, each square ring acts as an individual resonating element. By exciting the elements in sequence with different phase delays through the slot radiator, the generated antenna beam can be steered. In the first design, the position of the single-slot radiator is shifted to achieve the beam steering functionality; while for the second antenna, to avoid mechanically moving the feeding slot, a double-slot-feeding structure is proposed with two slots excited with varying phase differences. Simulation and experimental results show that beam steering angles of −35° to 35° can be achieved for the single-slot-feeding design and beam steering angles of −30° to 30° are realizable for the double-slot-feeding configuration. Comparing with conventional phased array antennas, our proposed designs have compact size with moderate to high antenna gain.