Ultra-wideband and low-loss linear-to-circular polarizer based on multilayer frequency selective surface

Linear-to-circular (LTC) polarizers based on frequency selective surfaces (FSSs) are evolving and upgrading; however, designing polarizers with low loss and broad band is still a challenging task. To upgrade the polarizer, this paper proposes an ultra-wideband and low-loss LTC polarizer composed of FSSs. In each layer of the polarizer, two sides of the substrate are covered by inductive and capacitive patterns, respectively. For this reason, the constant transmission phase differences are acquired within wide band. And stacking four layers of FSSs is effective to improve performances of the proposed polarizer. What’s more, the extra sheets are added in the middle of adjacent FSSs to reduce the distance between layers. Finally, the thickness is reduced by 29.1% and the performances of polarizer are almost unaffected. Under normal incident wave, the simulated results show that the 3-dB axis ratio (AR) bandwidth is 93%. The total transmittance is better than − 0.5 dB when the linear polarized waves pass through the polarizer within 6–13 GHz. In addition, the proposed LTC polarizer exhibits a stable response with wide incident angle variation. The experimental data closed to the simulated results have been obtained.