Local constitutive parameters of metamaterials from an effective-medium perspective

The reason of the nonlocality of constitutive (material) parameters extracted from the Fresnel-type reflection-transmission coefficients of composite slabs at moderately low frequencies is explained, and the physical meaning of these parameters is clarified. Local constitutive parameters of metamaterial lattices are discussed, and their existence at moderate frequencies is demonstrated. It is shown how to extract local material parameters from the dispersion characteristics of an infinite lattice and from reflection and transmission coefficients of metamaterial layers.