High-frequency electromagnetic non-destructive evaluation for high spatial resolution, using metamaterials

Abstract

This study presents a new high-frequency electromagnetic method for a non-destructive evaluation of metallic strip gratings from printed circuit boards and of some carbon-fibre-reinforced plastic composites, allowing the detection of small defects. The electromagnetic transducer is based on a metamaterial lens realized with two conical Swiss rolls, that allows the transmission and intensification of purely evanescent modes generated in the slits of metallic strip gratings and in the dielectric that insulate the carbon fibres between them. The method and the transducer used allow the localization of metallic strip interruptions whose widths are greater than 0.2 mm, the non-alignment of carbon fibres, the breaking of carbon fibres, the lack of resin or delaminations due to impact at low energies, with spatial resolution being greater than 0.1 mm.