Ultra-broadband and high-efficiency reflective linear polarization convertor based on planar anisotropic metamaterial in microwave region

A simple design of an ultra-broadband and high-efficiency reflective linear polarization convertor with 90° rotation is presented in the microwave region. This convertor is formed from the planar anisotropic metamaterial (MM) using cut-wire (CW) structure. Three resonance modes are generated by electric and magnetic fields of incident wave, which lead to bandwidth expansion extremely of cross-polarization reflection. The simulation result shows that a linearly polarized wave can be converted into its orthogonal polarization after reflection, the polarization conversion ratio is above 90% in the frequency range of 5.1-12.1 GHz and the relative bandwidth is up to 78.6%, which agree well with the experimental results. Both simulation and experiment results demonstrate the capability of linear polarization conversion by 90° with high polarization purity after reflection in the above frequency range, which can be confirmed by ellipticity η and the polarization rotation azimuth angle θ. The designed structure that utilized to build the thin MM slab is about λ0/8.72 evaluated at operating center frequency. It has application values in polarization control with high performances.