The Expanding Effect of Scanning Angle for Small-Aperture Phased Array Antenna by Huygens' Metasurface-Based Radome

A new application of the radome is to enhance the scanning range of the antenna, which can be realized by surrounding the antenna with a voltage-controlled active frequency selective surface (AFSS) [1] or loading a high- transmittance active metasurface [2] . For passive application, the thickness or the equivalent dielectric constant of the hemispherical radome needs to be changed at different positions to achieve a wide range of refraction angle of the incident beam [3] . Huygens' metasurface (HMS), which consists of electric and magnetic dipoles, is a novel kind of metasurface with a high transmission efficiency. By combining the orthogonal electric dipole and the magnetic dipole in each Huygens’ meta-atom, HMS meta-atoms can provide the full 2π range of phase change with arbitrary transmission amplitude for line polarization wave. In microwave region, metal strips and metal rings printed on the dielectric substrate are the simplest structures adopted to construct the required electric and magnetic dipoles, which makes the Huygens' metasurface-based radome a potential application for beam steering. Here, a novel method to enhance the scanning angle of phased array antenna utilizing passive gradient phase metasurface is proposed to achieve planarization and thickness reduction.