LTC polarization-converted metamaterial based on hybrid EIT-like effect of bright-bright and bright-dark coupled modes

This paper proposes a high-efficiency linear to circular (LTC) polarization conversion metamaterial based on a multi-mode electromagnetically induced transparency-like (EIT-like) effect in the microwave band. The EIT-like transmission windows of bright-bright (B-B) and bright-dark (B-D) modes are constructed by generating multi-path excitation through an asymmetric structure. Then, the frequency shift and phase differences of the TE- and TM-polarized EIT-like windows are achieved by the perturbation method, which attributes to an LTC polarization conversion response with a high efficiency of 99.8%. The perturbation method also contributes to the insensitive performance for both EIT-like and LTC windows, corresponding to polarization angles of 240° and 120°, respectively. Finally, the proposed structure is fabricated and measured, and the simulation and experimental results are in good agreement.