An Ultra-wideband Metamaterial Absorber with Angular Stability

In this paper, an ultra-wideband (UWB) microwave absorber with robust angular stability is proposed. Each unit of the structure consists of three-layer stacked resistive films to effectively broaden the absorption bandwidth. A metallic via is inserted in the center of the structure, which effectively guides the TM polarization oblique incident wave power to propagate vertically and be absorbed by the resistive films, thus enhancing the angular stability of TM polarization. Within the frequency range of 3.2 GHz to 35.5 GHz, the absorptivity surpasses 90% and the fractional bandwidth reaches 167%. Within an incident angle range of 0∘ to 60∘, the absorptivity of TE polarization remains at about 80%, and the TM polarization can be maintained at over 90%. The absorption mechanism was analyzed by surface power loss and surface current distribution. A sample was fabricated, and the measured results are consistent with the simulated ones. The absorber displays good angular stability and broad bandwidth, making it ideal for electromagnetic stealth applications.