A Wideband Microwave Absorber Compatible With Infrared Stealth Based on the Design of Magnetic Loss Layer

Microwave absorbers (MAs) have been required to possess ultrawide effective absorption bandwidth (EAB), infrared stealth, thin thickness, and lightweight for applications in microwave technology and multispectral stealth with increasingly complex electromagnetic (EM) environments. However, there remains a challenge to achieve ultrawide EAB while pursuing thin thickness. Herein, MA (MA-V-2) was constructed by introducing resistive film (RF), infrared stealth layer (IRSL) and magnetic loss layer into polymethacrylimide (PMI) foam. The patterns of RF were optimized by genetic algorithm to obtain broadband absorption at high frequency, and then the magnetic loss layer containing carbonyl iron step-like structure and resonant ring was designed to drive EAB to step into low frequency. Te MA-V-2, thus, achieves ultrawide EAB of 2–18 GHz with a thickness of 7 mm, only 90.01% of the limit thickness for nonmagnetic absorbers. Meanwhile, it also possesses good infrared stealth with an average infrared emissivity of 46.77% (3– $14~\mu $ m). This work, therefore, clarifies that the introduction of a designed magnetic structure can effectively break the limit between thickness and broadband absorption, providing an effective strategy for the development of broadband, lightweight MAs with thin thickness.