Transparent and tunable water-based metamaterial absorber with low infrared emissivity

A transparent and tunable metamaterial absorber with simultaneously low infrared (IR) emissivity is proposed in this Letter. The designed structure consists of an infrared shielding layer (IRSL), a radar absorber layer (RAL), and an air/water dielectric layer with an indium-tin-oxide (ITO) backplane. Both the IRSL and RAL are made of ITO films and polyethylene terephthalate substrates, so the absorber exhibits optical transparency. By changing the thickness of the water layer, the 90% absorption band can be converted from 7.6–12.5 to 12.8–18.2 GHz. The absorber is polarization insensitive and stable at wide incidence angles. The IR emission value of IRSL is 0.24. Both numerical simulations and experimental measurements demonstrated the good performance of the proposed structure, indicating its great potential applications in multi-spectrum compatible stealth.