Low profile and broadband circularly polarized metasurface antenna based on nonuniform array

Abstract

A broadband low-profile, circularly polarized metasurface antenna with a nonuniform aperture is proposed for L band satellite communications. By optimizing the nonuniform geometry, antenna size is minimized and bandwidth is expanded. Characteristic mode analysis (CMA) clearly reveals the dominant modes and stimulated modes for wideband operation. The feeding structure employs a quadrature phase quarter-power divider to excite a collection of orthogonal modes, generating stable circular polarization (CP) radiation and a phase center. Numerous feeds and crossing slots, in conjunction with the metasurface, produce multiple resonances and minimum axial ratio (AR) locations when excited, resulting in a broad impedance and AR response. The low profile nonuniform metasurface CP antenna achieves a 40% −10 dB impedance bandwidth, a 47% 3 dB AR bandwidth, and a peak gain of 8.7 dBic with a compact dimension of 0.67 × 0.67 × 0.06 λ3.