Water-based Metamaterial with Thermal Tunability for Dual-band Absorption

A water-based metamaterial absorber (WMA) is designed and simulated to achieve dual-band absorption in this paper. The WMA consists of a cross-shaped resonator at the top, a water-filled container in the middle, and a metal backplane at the bottom. When the container is filled with water, the excellent absorption performance is achieved in two frequency bands (4.22–4.83 GHz and 11.72–17.20 GHz). Furthermore, the WMA is thermo-tunable when temperatures change from 10° to 60° and the WMA has the characteristics of wide angle incidence and polarization insensitivity. In addition, the WMA without top metal dielectric substrate has an absorption rate of more than 90% at 4.3–5.0 GHz. As expected, the WMA can be applied to reduce broadband scattering and collect electromagnetic energy.