A High-Efficiency 90° Polarization Rotator Based on Split-Ring Resonators

Based on the regulation of the polarization state of electromagnetic(EM) wave by metamaterials, the application of polarization rotator in C-band is studied in this paper. Firstly, a double-layer 90° polarization rotator is proposed and analyzed. The top layer is a split-ring resonator, the bottom layer is a grating, and a Fabry-Perot(F-P) cavity is formed between them to enhance the polarization conversion efficiency. Results show the polarization is able to rotate vertical incident linearly polarized waves by 90° in the frequency range from 6.50 to 7.20 GHz. The cross-polarized transmission component can only reach 75%, so a three-layer 90° polarization rotator is proposed to improve it. The simulation results show that the frequency band from 6.47 to 7.21 GHz with a minimum of 98% cross-polarization transmission coefficient is achieved, co-polarization transmission coefficient is less than 5%, and the cross polarization transmission coefficient is up to 99.48% at the resonant frequency.