An angularly stable dual-broadband anisotropic cross polarization conversion metasurface

Abstract

A dual broadband anisotropic cross-polarization-conversion (CPC) metasurface is designed and tested. The unit cell of the proposed metasurface consists of a two-slit rectangular split-ring-resonator inside of which a metallic cross element is placed. The unit cell is printed on a dielectric substrate backed by a metallic plane. Excellent CPC is achieved in two wide frequency bands from 5 to 9.7 GHz (4.7 GHz bandwidth) and from 11.2 to 15 GHz (3.8 GHz bandwidth) for both normal and oblique incidences. The wide CPC bandwidth is due to the plasmonic resonances occurring at three distinct frequencies. The unique physical structure, sub-wavelength size, and electrically small substrate thickness make the response of the metasurface identical for both x and y polarizations and insensitive to incidence angles (up to 60°). The physical mechanism behind polarization conversion is also elucidated through surface current distribution and through the concept of a high impedance surface. The proposed design is validated by full-wave simulations and experimental measurements.