Electromagnetic non-destructive evaluation using metamaterials

This paper proposes the study and implementation of metamaterials in electromagnetic non-destructive examination; these materials can serve as electromagnetic flux concentrators in the radio frequency range. Thus, the use of new types of metamaterials, namely conical Swiss roll, is proposed. Here, we present a method of extracting the necessary parameters (effective magnetic permeability and the frequency) from the data obtained by measuring network parameters. Due to the fact that conical Swiss rolls can serve as radio frequency flux concentrators, they can be used in the fabrication of electromagnetic lenses, being designed on the basis of Fourier optic principles. As a direct application, carbon fibre reinforced plastic (CFRP) plates with and without delaminations, created by impacts with low energy, were examined by means of electromagnetic transducers with a metamaterial lens. The characteristics of a carbon fibre woven structure become visible and the delaminations are clearly emphasised.