Retrieval of effective parameters of left handed materials by using different approaches

Two different expressions are used in this paper to extract bulk electromagnetic properties matching to effective permeability and permittivity, which characterize metamaterials. These parameters have been determined by calculation of S-parameters. We use global approaches with these different analytical methods of calculation. This choice of global approaches is justified by the fact that negative refraction index metamaterials belongs to particular category where the limits of validity of the effective medium theories are not defined. For designing and testing the studied structure, we use HFSS software as a computational approach based on finite element method.