View article

We discuss the validity of standard retrieval methods that assign bulk electromagnetic properties, such as the electric permittivity and the magnetic permeability , from calculations of the scattering parameters for finite-thickness samples. -parameter retrieval methods have recently become the principal means of characterizing artificially structured metamaterials, which, by nature, are inherently inhomogeneous. While the unit cell of a metamaterial can be made considerably smaller than the free space wavelength, there remains a significant variation of the phase across the unit cell at operational frequencies in nearly all metamaterial structures reported to date. In this respect, metamaterials do not rigorously satisfy an effective medium limit and are closer conceptually to photonic crystals. Nevertheless, we show here that a modification of the standard -parameter retrieval procedure yields physically …