multi-band asymmetric transmission and 90° polarization rotator based on bi-layered metasurface with f-shaped structure

In this paper, a chiral metamaterial consisting of bi-layered metasurface with double f-shaped resonators is investigated. we experimentally demonstrate that this new structure can realize multi-band asymmetric transmission of a linearly polarized wave in the microwave region. the simulated results also show that the structure can achieve multi-band 90° polarization rotator for a y-polarized wave. the mechanisms of coupling modes are analyzed by the current distribution at different resonant frequencies, which indicates that the cross-polarized transmission is due to both the electric coupling and the magnetic coupling. furthermore, the polarization conversion ratios (pcrs) with more than 90 % conversion efficiency of x-polarized and y-polarized waves are also studied based on the optical activity and electric field distributions.