Ultra-thin Optically Transparent Broadband Microwave Metamaterial Absorber Based on Indium Tin oxide

A broadband metamaterial absorber (MMA) with optical transmittance property was designed to address the electromagnetic (EM) pollution in gigahertz (GHz). The proposed MMA with high optical transmittance polymethyl methacrylate (PMMA) between a periodic arrayed indium tin oxide (ITO) film and a low-resistivity ITO reflective layer. Over 90% microwave absorbance can be achieved in the frequency range of 6-17.8 GHz and three distinct absorption peaks can be found in the reflection spectrum. The results also show wide-angular stability, good polarization insensitiveness, and optical transmittance properties. The microwave attenuation mechanisms of the proposed MMA were investigated using surface current distribution and power loss density. The excellent microwave absorption and optical transmittance properties indicate that the designed MMA has strong potential for developing optical transmittance microwave absorption windows and devices.