Ultrabroadband Metamaterial Absorber Based on Effectively Coupled Multilayer HIS Loaded Structure With Dallenbach Layer

Abstract

An ultrawideband metamaterial absorber is demonstrated in the radar frequency range. The absorber features a thin thickness and outstanding broadband absorption performance. Effective absorption was obtained based on the loss of multilayer high-impedance surface (MHIS) loaded electromagnetic (EM) absorber and the Dallenbach layer. The impedance of the MHIS loaded EM absorber was analyzed to resolve the high-frequency broadband absorption. We explained the reason for the resonance shift of the Dallenbach layer and obtained the related impedance relation. Numerical simulations were carried out, and the results are in agreement with the theoretical analysis. We investigated the absorption mechanism by analyzing the distributions of electric and magnetic fields, and the standing wave effect on the surface of the resistive film is explained. Experiment characterizations have been carried out to demonstrate that the absorption is improved by the effective coupling of the Dallenbach layer. The absorption of the structure with magnetic material (MM) has been improved in the low-frequency range of 1–5.65 GHz with the maximum value of 92% at 2.44 GHz. A wonderful approach has been proposed: the Dallenbach layer placed under the MHIS loaded absorber fully exerts a low-frequency absorption effect to broaden the absorption band.