A Circularly Polarized Metasurface Antenna Based on Holographic Method

In this paper, a new method for designing circularly polarized (CP) antenna is proposed, which combines the optical holographic principle and the structure of a center-fed parallel-plate waveguide. The proposed CP metasurface antenna is synthesized using a parallel-plate waveguide excited by a coaxial feed in the center of the lower plate and a non-uniform array of subwavelength slot-shaped cells. By means of slotting the top layer of the parallel-plate waveguide at the specific positions, the unit cells can couple to the cylindrical reference wave excited by the feed, radiating the power into the expected direction. This antenna has the advantages of low profile, small size, and ease of fabrication, requiring no feeding networks or shifting circuits to realizing beamforming. As the design example, a holographic metasurface antenna generating a right-hand circularly polarized wave (RHCP) is demonstrated numerically with simulation results.