The characterization of electric and magnetic properties of materials (simple or compound) and artificial structures (metamaterials) is an essential requirement for the correct design of our products as well as for the analysis of the electromagnetic issues of our clients. For example, with the knowledge of effective electric permittivity and effective magnetic permeability of a frequency selective surface, it is possible to previously estimate the effective shielding effect of such surface. Further more, even though the electromagnetic properties of conventional materials (e.g., metals, dielectric substrates, etc.) are in general well known in the microwave and optical regime, this is not the case in the Terahertz range (0.3-10THz). This emphasizes the importance of material characterization, in which TAFCO offers ad-hoc consulting services to meet our clients specific needs.