Moth‐Eye‐Inspired Gradient Impedance Microwave Absorption Materials with Multiband Compatible Stealth Characteristic

Abstract There is an urgent need to develop microwave absorbing materials with ultra‐broadband absorption and multiband stealth compatibility, but this is difficult to achieve due to the difficulty of perfect electromagnetic impedance matching. Therefore, inspired by the anti‐reflection moth eye model, this article prepares carbonyl iron (CIP)/polyurethane (PU) absorbing materials into three biomimetic structures of cylinder, circular cone, and semi‐ellipsoid structures to optimize the absorption performance, which realizes the effective absorption of 5.13–18 GHz. The simulation models proved that the biomimetic structures can improve the anti‐reflection performance by building gradient impedance inside the materials. Finally, under the synergistic action of multiple reflection and gradient impedance mechanisms, the effective absorption bandwidth (EAB) of the semi‐ellipsoid moth eye biomimetic structure material with a total thickness of 3 mm can reach 6.94 GHz. The material can still achieve the EAB of 6.84 GHz with a low infrared emissivity of 0.242 by constructing the double‐layer structure. This work effectively solves the problem that the EAB of traditional microwave absorbing materials is difficult to be broadened due to impedance mismatch, and puts forward a new idea for optimizing the performance of microwave absorbing materials and compatible stealth.