A New Compact Ultra-Thin Circularly Polarized True Metasurface Antenna

We present a novel design for a True Metasurface Antenna (TMA) that is compact, ultrathin, and inspired by the traditional circularly polarized microstrip patch antenna array. This approach involves modifying the feed point location and incorporating a rectangular slot on top metallic layer of each electrically small resonator. This ultra-thin antenna efficiently occupies a small area of $1.65 \lambda_{0} \times 1.65 \lambda_{0}$ at the resonance frequency of 5.8 GHz. In addition, this TMA has a gain of over 14 dBi and is comprised of two layers of Rogers RO4003 substrate. Each layer has a thickness of 0.813 mm and there is no additional air gap between the layers. Numerical results show that the proposed circularly polarized TMA has a radiation efficiency of $87.5 \%$ and an aperture efficiency of $79.5 \%$ at 5.8 GHz.