Low-Profile Transparent Ultrabroad Dual-Transmission-Band Frequency Selective Rasorber Using Low-Resistive ITO Film

This communication presents a design method to use low-resistive indium tin oxide (ITO) film for forming a low-profile and transparent dual-polarized frequency selective rasorber (FSR) with two ultrabroad transmission bands. The FSR designed by stacking two lossless dual-passband Frequency-selective surface (FSS) with a 2-mm air gap achieves two absorption bands by means of the interlayer coupling effect between the top and bottom FSS. The designed FSR realizes two broad transmission bands of 4.16–11.35 GHz (92.7%) and 18.89–30.06 GHz (45.6%), respectively while two broad absorption bands cover 13.54–16.58 GHz (20.2%) and 31.33–35.81 GHz (13.4%), respectively. A prototype of the proposed FSR is fabricated to verify its absorption and transmission performance, and the working principle is analyzed by combining the equivalent circuit model (ECM) with the surface current distribution. The proposed FSR exhibits the potential to reduce the out-of-band radar cross section (RCS), with its optical transparency showing promise for window applications.