Thin Multispectral Camouflage Absorber Based on Metasurfaces with Wide Infrared Radiative Cooling Window

Abstract

Herein, a hierarchical metamaterial (HMM) is reported to achieve multispectral camouflage for thermal infrared detectors and radar. The HMM consists of a frequency‐selective emitter (FSE) integrated with a microwave absorber (MA). The FSE layer has an average absorptivity of 0.18, 0.85, and 0.18 in the wavelength of 3–5, 5–8, and 8–14 μm, respectively, in the case of the normal incidence. The absorptivity of MA maintains more than 91% (87%) in the broadband of 8–12 GHz (the entire X‐band) up to incident angles of for TM (TE) polarization. Overall, the average surface emissivity of HMM is 0.25, 0.86, and 0.26 in the infrared broadband of 3–5, 5–8, and 8–14 μm, respectively. The FSE considers infrared camouflage and infrared radiative cooling. The performance of HMM in microwave range remains unchanged, compared to MA structure without FSE layer. From the point of view of thickness, the HMM structure is only 2.34 mm. These excellent performances indicate that the herein described proposed HMM has promising applications in multispectral camouflage fields.