Single-Layer Broadband Optically Transparent Metamaterial Absorber Using Gold Thin Film

This article introduces a novel design for a thin, single-layer, optically transparent microwave metamaterial absorber. The proposed structure is composed of a polycarbonate (PC) substrate with two sides coated with gold films of a few tens of nm thickness via thermal evaporation. A specific periodic pattern is etched onto the upper side of the substrate using the optical lithography technique, while the bottom side serves as the electrical ground plane. The absorber’s performance was analyzed using comprehensive full-wave electromagnetic (EM) simulation and equivalent circuit modeling, which were validated by experimental measurements, showing excellent agreement. The fabricated transparent absorber demonstrated over 90% absorption in a broad bandwidth (BW) from 8.5 to 23 GHz, covering
$X$
,
$Ku$
, and a portion of
$K$
bands, with an average optical transparency of approximately 75%. Our full-wave simulation results showed that the proposed absorber’s performance is highly insensitive to the incident angle and polarization angle due to its symmetrical pattern. The proposed single-layer absorber has a thin, rigid structure with high transparency, making it suitable for various real-world applications.