Wideband linear-to-circular polarization conversion realized by a transmissive anisotropic metasurface**Project supported by the National Natural Science Foundation of China (Grant No. 61471387) and the Research Center for Internet of Things and Big Data Technology of Xijing University, China.

Abstract

We propose a metasurface which consists of three conductive layers separated by two dielectric layers. Each conductive layer consists of a square array of square loop apertures, however, a pair of corners of each square metal patch surrounded by the square loop apertures have been truncated, so it becomes an orthotropic structure with a pair of mutually perpendicular symmetric axes u and v. The simulated results show that the metasurface can be used as a wideband transmission-type polarization converter to realize linear-to-circular polarization conversion in the frequency range from 12.21 GHz to 18.39 GHz, which is corresponding to a 40.4% fractional bandwidth. Moreover, its transmission coefficients at x- and y-polarized incidences are completely equal. We have analyzed the cause of the polarization conversion, and derived several formulas which can be used to calculate the magnitudes of cross- and co-polarization transmission coefficients at y-polarized incidence, together with the phase difference between them, based on the two independent transmission coefficients at u- and v-polarized incidences. Finally, one experiment was carried out, and the experiment and simulated results are in good agreement with each other.