Parametric retrieval of effective constitutive parameters of split-ring resonator metamaterial

Abstract

ABSTRACT Metamaterials are periodic artificial composite materials structured on a sub-wavelength scale. The most interesting physical characteristic of these materials is the negative refractive index. In ordinary materials, permittivity and permeability are positive, while metamaterials may have negative permittivity or permeability or both. In this article, a method for recovering with certain accuracy the effective parameters based on the determination of transmission and reflection S-parameters are presented. The studied structure consists of a dielectric substrate and several metallic split-ring metal resonators arranged periodically. These S-parameters allow to determine all the effective parameters by using retrieval analytical models. The variation of the resonance frequency and the amplitudes of the effective parameters according to geometrical parameters of two metal rings of the SRR cell, of the dielectric constant of substrate or of the rotation of the outer ring relative to the inner ring are illustrated. We noted that the structure has a bi-anisotropic character. The results also show that a tuning metamaterial can be implemented by simply changing the dimensions or orientation of metal inclusions or substrate properties. The accurate Tailoring and retrieving of effective constitutive parameters of the analysed metamaterial slabs are of extreme importance for further development of new microwave antennas and filters.