Oblique incidence optimal design of microwave dielectric-magnetic absorbing composites

The impedance matching equation of a single-layer dielectric-magnetic absorber excited by an oblique incidence plane wave is resolved with an expression providing the optimal thickness and highlighting the composite crucial parameters. The effective propagation constant of the nonuniform refracted plane wave into the absorber is represented by a new formulation as a function of the true refraction angle which is a real number unlike the complex quantity resulting from the Snell's law, usually applied in the literature. The proposed design process is applied to compute microwave absorption performances of different dielectric-magnetic materials, considering both normal and oblique incidence. Furthermore, the incidence angle effect is investigated.