Compact asymmetric metamaterial circular polarization transformer based on twisted double split-ring resonator structure

In this paper, a compact asymmetric metamaterial circular polarization transformer using twisted double square split-ring resonator was proposed and investigated experimentally and numerically. This compact structure can convert an incident linearly y-polarized (x-polarized) wave propagation along the −z (+z) direction to the transmitted right-hand circular polarization (RCP) and left-hand circular polarization (LCP) at 7.3 and 8.3 GHz, respectively. The difference in level between the transmitted waves with LCP and RCP can reach more than 35 dB at the resonant frequencies. The experiment results are in good agreement with the numerical results. The surface current distributions on the structure are analyzed to illustrate this linear to circular transformation phenomenon.