Ultra broadband metamaterial absorber with oblique incidence based on effective medium theory

We demonstrate the design, measurement, retrieval effective parameters and calculations of an ultra-broad band metamaterial absorber (MMA), in which the metallic resonant structures including the inserted chip resisters and the substrate are equivalent to a homogeneous and isotropic effective medium. The effective electromagnetic (EM) parameters are retrieved by extracting the reflected and transmitted coefficients, and absorbance of the MMA is calculated by the retrieved effective EM parameters based on effective medium theory. The calculated results are in good agreement with simulations and experiments.