Improving broadband absorption and transparent properties for microwave metamaterial via stimulating bimodal effect with induced water substrate

In this paper, a frequency selective microwave absorber is designed and demonstrated with water as the substrate layer, which realizes >90% absorption in the frequency range of 7.3-20 GHz and 73.6% light transparent in the spectrum range of 400-800 nm. The improved absorption is believed to be attributed to the synergy between the intrinsic resonance of the ITO metasurface and the new resonance excited by the substrate water layer. Particularly, the light transparence of the absorber is improved with the introduced water layer. Therefore, the proposed absorber shows excellent comprehensive performances for high optical transparent microwave broadband absorbers.