Ultra-wideband transparent indium tin oxide metamaterial absorber with wide-angle and polarization-insensitive properties

A metamaterial absorber (MA) presents features such as ultra-wideband performance, optical transparency, wide-angle, and polarization-insensitive. The basic component consists of a three-layer ITO patterned resistive film embedded in a transparent polyvinyl chloride dielectric substrate. By optimizing the structural parameters, the MA achieves an absorption rate exceeding 90% within the bandwidth range of 3.76–26.72 GHz, effectively covering the entire C, X, Ku, K, and Ka bands, with a relative absorption bandwidth of 150.62%. Furthermore, the proposed MA demonstrates polarization insensitivity at wide angles, with incident angles of 45° for TE polarization and 60° for TM polarization. It also exhibits a commendable optical transmittance of 65%. The microwave loss mechanism of the MA is further investigated by analyzing the distribution of the electric field, magnetic field, power loss density, and surface current through the principle of impedance matching. The experimental results align with the numerical simulation results, thereby validating the effectiveness of the structural design. This optical transparent ultra-wideband MA, characterized by wide-angle and polarization insensitivity, introduces novel concepts for radar stealth optical windows.