Anisotropic impedance metasurface enabled dual-band short backfire antennas with high aperture efficiency

A dual-band short backfire antenna with high aperture efficiency for satellite communications is presented. The high aperture efficiency is enabled by loading anisotropic impedance metasurfaces (AIMs) to the cavity walls of a hexagonal short backfire antenna fed by a slot-loaded suspended patch. By optimizing the surface impedance values of the AIM loadings, the achieved aperture efficiency averaged over the GPS L2 and L1 bands is 90.5% for a hexagonal SBFA. The corresponding efficiency for a circular SBFA with cavity walls is 99%. Cross-polarization is also greatly improved. The homogeneous AIM can be realized by a finite periodic array of low-loss electric resonators that are comprised of metallic patterns.