This communication presents a low-profile fully metallic high gain circularly polarized resonant cavity antenna, with a novel single-layer metasurface as superstrate operating at 300 GHz. The unit cell of the metallic metasurface layer consists of perforated grids of hexagonal and octagonal-shaped radiating apertures. The metasurface superstrate layer acts as a polarization convertor from linear-to-circular, which provides left-handed circularly polarized (LHCP) radiation. For simplicity and less design difficulty, a low cost laser cutting brass technology is proposed to design the antenna at sub-terahertz. The proposed circularly polarized resonant cavity antenna prototype has a low-profile planar metallic structure of volume 2.6λ0×2.6λ0×1.24λ0. Experimental results validate the design concept. The antenna yields a measured LHCP gain of 16.2 dBic with a directivity of 16.7 dBic at 302 GHz. This proposed circularly polarized resonant cavity antenna finds potential application in 6G sub-terahertz wireless communications.
Keywords: 6G wireless communication; circularly polarized (CP); laser-cutting technology; metasurface (MTS); resonant cavity antenna (RCA); sub-THz.