A Dual-Layer Full-Phase Frequency-Selective Surface for Continuous 2-D Beam Scanning

Based on the generalized frequency selective surface (FSS) theory, we prove that the dual-layer dual-polarization transmission FSS can achieve 360° phase coverage at a limited loss. As a verification, a dual-layer dual-polarization full-phase unit cell with vias is proposed, which can achieve a phase range of more than 360° under 2 dB transmission loss. In addition, we innovatively apply the proposed dual-layer full-phase FSS to the design of a continuous 2-D beam scanning antenna based on the Risley prism (RP). This scheme effectively reduces the number of dielectric substrate layers required by the phase shifting surface (PSS), reduces the rotating scanning inertia, and effectively improves the aperture efficiency. The measured results show that the maximum scanning range of the 2-D beam scanning antenna can reach ±46° in the elevation plane and 360° in the azimuth plane. When operating at the center operating frequency of 21 GHz, the maximum gain of the antenna is 35.75 dBi with an aperture efficiency of 44.1%.