Low-profile antennas with 100% aperture efficiency based on cavity-excited omega-type biansiotropic metasurfaces

We propose a novel concept for highly-directive low-profile antennas, based on a single localized source embedded in a cavity, covered by an omega-type bianistoropic metasurface (BMS). We show that such metasurfaces, which include subwavelength particles with electric and magnetic polarizabilities, and magnetoelectric coupling, allow control of both the aperture field phase and the BMS reflection coefficient, without requiring active or lossy components. Subsequently, we use this degree of freedom to exclusively excite the highest-order fast lateral mode, guaranteeing optimal aperture illumination efficiency for arbitrarily-large apertures, without incurring edge-taper losses. We verify our semianalytical calculations with full-wave simulations, showing that the proposed antenna can outperform our previously-introduced cavity-excited Huygens' metasurface antenna, offering a simple and efficient design for compact high-gain antennas.