Microwave Polarizer Based on Complementary Split Ring Resonators Frequency-Selective Surface for Conformal Application

In this paper, a microwave polarizer based on frequency selective surface (FSS) loaded with complementary split ring resonator (CSRR) for non-planar and conformal application is presented. The frequency-selective polarizer is fabricated on liquid crystal polymer substrates (LCPs) material with $50\mu \text{m}$ thickness, which shows very good mechanical flexibility for microwave band. The Frequency-selective polarizer consists of a metal FSS screen pair with double complementary split ring resonators aligned in the vertical direction without any displacement. The substrate integrated waveguide (SIW) cavity was introduced to enhance the Q-factor of the CSRR particles and the mechanical strength of the FSS screens at bending conditions. The measured results show that the CSSR-FSS polarizer with the minimum transmission loss for TE-polarization incidence wave is 0.75dB at the 10.24 GHz and 19.05 dB for TM-polarization incidence wave, with an extinction ratio of 18.3dB. Finally, the oblique incidence from normal to 60 degrees and bending tests with the bending radius of 9.8 cm and 8.8 cm of the CSRR-FSSs were also carried out, and the measured results indicate that the CSRR-FSS show a low susceptibility to bending behavior at the small bending radius beyond the 8.8 cm and different incidence angles from normal to 45 degrees. Both the simulated and experiment data indicated that the proposed ultra-thin CSRR-FSS shows excellent flexibility and polarization selectivity.