Testing Electrophysical Parameters of Metamaterials by the Method of Surface Electromagnetic Waves

The development of metamaterials has led to the search and selection of effective methods for radio wave nondestructive testing of their electrophysical parameters. The existing approaches to testing, based on the recovery of the effective electrophysical parameters of metamaterials from the reflection and transmission coefficients of an electromagnetic wave, have low reliability and do not provide the local inspection of the parameters. In this paper, we propose for the first time a radio-wave method for local inspection of complex dielectric and magnetic permeabilities, as well as the thickness of flat-layered samples of metamaterials on a metal substrate using surface electromagnetic waves of the microwave range. The method is based on solving the inverse problem of determining the effective electrophysical parameters of a metamaterial from the frequency dependence of the complex attenuation coefficient of the field of a surface electromagnetic wave excited in the sample under study. In this case, the electrophysical parameters of the metamaterial are represented in the form of parametric frequency functions in accordance with the Drude–Lorentz dispersion models, and the solution of the inverse problem is reduced to minimizing the objective function constructed from the discrepancy between the experimental and calculated theoretical values of the attenuation coefficients of the surface electromagnetic wave field on a grid of discrete frequencies. The structure of the measuring complex that implements the proposed inspection method is presented. A sample of a flat-layered metamaterial based on SRR elements with a region of negative refraction in the frequency range of 10.06–10.64 GHz was investigated for the numerical and experimental verification of the method. Experimental verification has shown that the local values of the effective electrophysical parameters of the studied metamaterial differ from the calculated ones by no more than 10%.