Dual-Band Circular Polarizers Based on a Planar Chiral Metamaterial Structure

A novel dual-band chiral metamaterial (CMM) circular polarizer is proposed based on a dual-armed wheel-like structure. The proposed CMM can convert a linearly polarized electromagnetic wave into a circularly polarized (CP) mode. The simulation and measured results show, with good consistency, that the CMM exhibits good CP characteristics, such as a polarization isolation higher than 18 dB and an axial ratio lower than 1 dB. In addition, our studies show that all the resonance frequencies of this CMM structure are independent. Finally, a simple design method is presented and verified by a simulation to change the resonance frequencies of the proposed dual-band CMM circular polarizers.