Design and Broadband Absorption Properties of a Composite Metamaterial Microwave Absorber Based on the Debye Dielectric Loss Model

A broadband microwave composite metamaterial absorber based on the Debye model, consisting of triple dielectric loss layers and different-ordered metallic fractal pattern vertical layers, has been proposed. The research results show that when all the three dielectric layers are silicon carbide fiber (SiC_f), the composite absorber presents two intense absorption bands with a bandwidth of 5.44 GHz. The length (l) of the metallic pattern and thickness (t) of the top dielectric layer can effectively regulate the reflection loss performance. Additionally, the effective absorption bandwidth increases to 13.44 GHz when the relative absorption bandwidth reaches about 119.15% by replacing SiC_f at the top dielectric layer with the dielectric loss materials which satisfy the Debye model. The research results show that the absorption bandwidth obviously increases with dielectric loss materials of distinct Imε. Furthermore, the proposed fractal pattern shows robustness to the variation of complex permittivity spectrum, expanding the range of suitable dielectric materials for composite broadband metamaterial absorbers.