Sandra Gomez

Asymmetrical stripline based method for retrieving the electromagnetic properties of metamaterials

An experimental characterization technique for determining the electromagnetic properties of metamaterials in the microwave frequency band is presented. The method consists in measuring the S-parameters of an asymmetrical stripline partially filled with the sample to be characterized. For retrieving the characteristic parameters, two different approaches based on quasi-static approximations are compared. This measurement cell allows an “in situ” characterization because it reproduces the electromagnetic environment frequently found in planar technologies for microwave applications of metamaterials. The whole sample is uniformly excited in magnitude and direction by the interacting electromagnetic field which guarantees representativeness of extracted permittivity and permeability and avoids possible inconsistencies due to anisotropy and heterogeneity of metamaterials.

Electromagnetic characterization of metamaterials in the centimetric frequency band using an original adjustable height stripline

We propose a broadband measurement method for measuring the electromagnetic (EM) properties of metamaterials in the 1–6 GHz frequency range. For this experimental technique, an original adjustable height strip transmission-line was developed that makes it possible to characterize metamaterials with different volumes and different numbers of unit cells. Therefore, it was possible to assess the influence of the number of unit cells in a sample on the measured constitutive parameters (complex permittivity and permeability). This study enabled us to define the criterion of the representative elementary number of cells. This criterion must be satisfied in practice in order to determine the microwave behavior for the sample under test in as close as possible to an infinite medium, whose EM properties can only be determined from simulations. Experimental and theoretical results for split ring resonator-type metamaterials are presented, compared, and discussed.