UWB Transparent Metamaterial Absorber With Optimally Patterned Gold Nanolayer

A novel thin, optically transparent microwave metamaterial absorber (TMMA) is presented. The proposed structure utilizes a 3-mm-thick polycarbonate (PC) main substrate coated on both sides with 8-nm-thick gold thin films deposited via thermal evaporation. To achieve maximum absorption bandwidth, polarization insensitivity, and angular stability, the unit cell of the TMMA is optimized through a pixelation and binary optimization technique. This process results in an optimal pattern of gold nanolayer on the upper surface of the substrate. The resulting periodic pattern is transferred using optical lithography. The bottom gold film acts as the electrical ground plane. An additional 3-mm-thick PC superstrate is then incorporated to improve impedance matching and protect the coating of the main substrate. Comprehensive full-wave electromagnetic simulations are employed to assess the absorption performance. The design is subsequently validated through sample fabrication and experimental measurements. The proposed TMMA exhibits over 90% absorption within an ultrawideband (UWB) range of 5.1–25.2 GHz while maintaining an average optical transparency of approximately 70%. The symmetrical design additionally offers wide angular stability and minimal polarization sensitivity.