Triple-broadband asymmetric transmission via cross-polarization conversion based on composite chiral metasurface structure

In this paper, a novel composite chiral metasurface (CCMS) was proposed and investigated, which is composed of a rectangle -patch -ring resonator (RPRR) structure sandwiched between two twisted sub -wavelength metal gratings separated by a dielectric substrate. Both simulation and experimental results demonstrate that the proposed CCMS achieves a significant asymmetric transmission (AT) effect and efficient cross -polarization conversion for the incident linear polarization wave in a triple -broadband range. Simulation results are in good agreement with the experiments. Specifically, the CCMS converts normal impinging y -/x -polarization wave along the forward/backward (-z/ +z) direction into transmitted x -/y -polarization wave with the crosspolarization transmission coefficient over 0.7 at 4.15-5.5 GHz, 7.29-10.77 GHz and 12.49-16.59 GHz, respectively. In addition, the AT coefficient ( Delta lin ) and the total transmittance ( T x ) of the x -polarization wave propagation along the -z axis direction are both over 0.5 in the triple -broadband frequency range. The simulated polarization azimuth rotation and ellipticity angles, induced surface current, and electric field vector distributions further confirm the characteristics of the triple -broadband high -efficiency AT effect and cross -polarization conversion of the designed CCMS. The proposed CCMS design serves as an important reference for practical applications of microwave devices.