Ultra-Broadband Polarization Conversion Meta-Surface and its Application in Polarization Converter and RCS Reduction

In this paper, an ultra-broadband and high-efficiency polarization conversion metasurface is presented in the terahertz region. The metasureface is similar to a sandwiched structure, which is composed of the top Double Split Ring Resonator (DSRR), an intermediate dielectric layer and a bottom metal layer. Both numerical simulation and theoretical calculation results demonstrate that the proposed metasurface can convert linearly co-polarized waves into cross-polarized waves in the frequency from 2.04 THz to 5.33 THz with a relative bandwidth of 89% and the polarization conversion ratio (PCR) is over 90%. Further simulation results show that the proposed metasurface is insensitive to the polarization angle, and the physical mechanism is revealed in detail by the surface current distribution. In addition, two different kinds of 2-bit coding metasurfaces are designed based on the Pancharatnam-Berry (PB) Phase. The simulated and calculated results show that the proposed PB-coding metasurface has excellent performance in flexibly controlling terahertz wave reflection and low Radar Cross Section (RCS). A 10dB RCS reduction can be achieved from 1.9 THz to 5.5 THz under normal incidence. It provides new degrees of freedom for studying terahertz wave manipulation and reducing RCS.