Ultra-thin optically transparent broadband microwave metamaterial absorber based on indium tin oxide

Broadband metamaterial absorber (MMA) with optically transparent property is essential for solving the elec-tromagnetic pollution problem at gigahertz. In this work, we designed and prepared a sandwich MMA consisting of high-transmittance substrate polymethyl methacrylate (PMMA), a periodically arranged indium tin oxide (ITO) film, and a low resistivity ITO reflective layer. The microwave absorbance over 90% can be achieved in the frequency range of 6-17.8 GHz. Wide-angular stability, good polarization insensitivity and optical transmittance to visible light (400-800 nm) are realized. The microwave attenuation mechanisms of the proposed MMA were investigated by surface current distribution and power loss density. The excellent microwave absorption and optical transmittance properties indicate the strong potential and feasibility of the designed MMA for the development of optically transparent microwave absorbing windows and devices.