Planar isotropic broadband metamaterial absorber

This paper presents a type of isotropic broadband metamaterial absorber comprising single-layer densely arranged hexagonal metal dendritic units having different sizes printed on an FR-4 dielectric substrate with a metallic film coating. The convergence of the different neighboring resonant frequencies of the differently sized units yields broadband absorption characteristics. In the case of normal incidence, the absorber operating in the X-band yields absorption rates greater than 80% in the frequency range from 9.05 GHz to 11.4 GHz, this reasonable absorption performance is maintained for oblique incidences less than 45°. The S-band absorber has an absorptivity of more than 50% in the frequency range from 3.02 GHz to 4 GHz. The experimental results demonstrate that the interaction between the different structural units is not obvious.