Metamaterials are artificial materials engineered to have electromagnetic properties that may not be found in natural media. A particular class of metamaterials is composed by compact FSS-like printed metallic layers, realized by patch-type or slot-type elements, with size small in terms of a wavelength. This kind of structures, due to the ease and low cost of manufacturing, may be efficiently employed to realize new type of devices like planar lenses and more generally focusing systems, cloaking or radar cross section reduction systems, and to improve the performance of existing devices like polarizers, frequency filtering materials and new types of radome for improving angular scanning capabilities of phased arrays (Wide Angle Impedance Matching). As a matter of fact, the capability of describing a three-dimensional periodic structure in terms of effective parameters is a key point for the synthesis of novel metamaterials with given properties. In the sub-wavelength regime, the FSS layers, constituent the metamaterial, can be modeled via an equivalent periodic transmission line; the latter can be analysed employing the Bloch theory, thus defining equivalent parameters that describes the electromagnetic behavior of the artificial material in terms of scattering parameters and dispersion properties. This allows the identification of the equivalent constituent parameters (permeability and permittivity) of the macroscopic homogenized medium. The desirable assumption of isotropic and spatially non dispersive medium often used in literature, is in most of the cases unrealistic. A more accurate description reveals indeed anisotropy and spatial dispersion …