Dual-Band and High-Efficiency Circular Polarization Convertor Based on Anisotropic Metamaterial

In this paper, a dual-band and high-efficiency circular polarization (CP) convertor based on anisotropic metamaterial (AMM) was proposed and investigated in microwave region. The proposed AMM based CP convertor is composed of a sub-wavelength metal grating sandwiched with bi-layered disk-split-ring (DSR) structure array, which can convert the normal incident CP wave to its orthogonal one around two adjacent frequency ranges. Based on the intrinsic anisotropic and Fabry-Perot-like cavity-enhanced effect, a high CP conversion efficiency can be achieved by applying the proposed AMM. Numerical simulation results indicate that the cross-polarization transmission coefficients can achieve maximum values of 0.84 at 4.5 GHz, and 0.92 at 7.9 GHz, respectively, which is in well agreement with experiment. In addition, the measured CP conversion efficiency is beyond 99% at resonance frequencies. The mechanism of the CP conversion properties can be explained by the electromagnetic (EM) interference model and the simulated electrical field distribution. Due to its excellent polarization conversion properties, the proposed CP convertor based on AMM structure shows potential application in such as radar, remote sensing, and satellite communication.