Asymmetric polarization converting metasurface for microwave applications

Abstract

In this paper, a triple-band polarization converting metasurface for X and K u band applications is investigated. The unit cell consists of an asymmetric circular ring, terminated with a T-shaped stub, printed on FR-4 substrate, and backed by copper cladding. The triple-band polarization convertibility of the metasurface results from the proper engineering and anisotropy along the x- and y-axis. The metasurface has three plasmonic resonances with a polarization conversion ratio (PCR) of almost 100% in the lower two frequencies bands and 95% in the higher frequency band. The plasmonic resonances at 8.2 and 13.6 GHz are due to magnetic dipole moment while response at 19 GHz is due to electric dipole moment. Cross linear polarization conversion, linear to circular polarization conversion, and circular to circular polarization conversion are observed, both for normal and oblique wave incidences. Measured and simulation results are in good agreement with an excellent polarization conversion in three frequency bands, i.e., 7.7 to 9.2 GHz, 10.8 to 15.5 GHz, and 17.5 to 19.2 GHz. The polarization conversion response of the metasurface is same for both x- and y-polarized waves and is quite stable under oblique incidence of the impinging wave. The metasurface dominates the merits of multi-band resonances, angle sensitivity, and higher PCR, and thus has eminent values for application in polarization-control appliances.