Dual-band linear-to-circular and circular-to-linear polarization converter based on reflective metasurface

In this work, a dual-band polarization converter is proposed based on a reflective metasurface. The metasurface is an appropriate anisotropic structure with a pair of mutually perpendicular symmetric axes x and y, and the reflection phase difference under x- and y-polarized incidences is very close to 90° in the two frequency ranges of 7.9–9.2 GHz and 12.4–25.2 GHz, so the metasurface can be used as a high-efficiency dual-band polarization converter to achieve both linear-to-circular (LTC) and circular-to-linear (CTL) polarization conversions in two separated frequency bands. The simulation and experimental results show that, when the dual-band polarization converter is under the incidence of u- and v-polarized waves, the reflected wave will be converted to a circular-polarized (CP) one in the two frequency bands of 7.78–9.38 GHz and 12.30–25.60 GHz, a dual-band LTC polarization conversion will be achieved with high-efficiency; in addition, under CP incidence, the reflected wave will be converted to a linear-polarized one in the two frequency bands of 7.76–9.39 GHz and 12.22–25.57 GHz, a dual-band CTL polarization conversion with almost the same working band and polarization conversion rate will be achieved. Therefore, the dual-band polarization converter has great potential application values in various polarization controlled devices.