A method for evaluating the dielectric properties of composites using a combined embedded modulated scattering and near-field microwave nondestructive testing technique

Investigation into the derivation of the dielectric properly of a material with an embedded modulated PIN diode-loaded dipole is described, using an open-ended rectangular waveguide as the irradiating source. Previous measurements of the curing of a mortar specimen show the sensitivity of this combined technique and its potential for inspecting composite structures. Modification of previous algorithms for back calculating the dielectric properties of a material with a conductor backing is considered. The modification would involve replacing the reflection at the conductor with the reflection at a modulated dipole antenna. For this, comparisons between the reflection coefficients of dipole antenna and an infinite conducting plate are made. These results are analyzed, and the necessary considerations are discussed.