Ultra-wideband Linear-to-Circular and Circular-to-Linear Polarization Conversion Realized by Anisotropic Metasurface

In this work, an anisotropic metasurface is proposed for linear-to-circular (LTC) and circular-to-linear (CTL) polarization conversions, which is composed of a square array of two-corner-cut square patches printed on a grounded dielectric substrate and covered by a dielectric layer. Numerical simulation results show that the anisotropic metasurface can act as a high-efficiency ultra-wideband reflective polarization converter to achieve both LTC and CTL polarization conversions. Under x- and y-polarized incidences, its reflected wave will be converted to left-handed and right-handed circular-polarized (CP) waves, respectively, in the ultra-wide frequency band between 7.14 and 25.66 GHz with a relative bandwidth of 113%, and the polarization conversion ratio (PCR) can be kept larger than 99.73% in the frequency range of 7.72–25.08 GHz; in addition, the reflected wave under CP incidence will be converted to an x- or y-polarized wave, and the bandwidth and PCR of the CTL polarization conversion are almost the same as those of the LTC polarization conversion. Finally, the working principle of the polarization converter is illustrated, moreover, an effective experimental verification is carried out, and a reasonable agreement is observed between the simulation and experimental results.