Determination of the Thickness and Dielectric Constant of a Dielectric Slab Backed by Free-Space or a Conductor through Inversion of the Reflection Coefficient of a Rectangular Waveguide Probe

Evaluation of thickness and material properties of coatings and dielectric slabs is an important practical issue. Microwave nondestructive testing techniques, using open-ended rectangular waveguide and coaxial probes have shown great potential for this purpose. However, to evaluate one parameter requires that the other be known a priori. This paper discusses the use of a relatively efficient method for evaluating both parameters simultaneously from measurements of the reflection coefficient of a test material. Results of two cases as well as a brief discussion of the limitations of the technique are provided in this paper