A Simple Non-Destructive Method for Characterizing Nondispersive, Low-Loss Dielectrics

It is shown how permittivity can be extracted via time domain reflection data from a perfect electric conductor (PEC) backed planar sample of a low-loss, non-dispersive dielectric using two rectangular Ku-band waveguide aperture probes with attached PEC flange plates of the same geometry but different dimensions. Of critical importance is being able to identify the reflection from the edge of the flange plate in the parallel plate region created by the plate and the PEC backing of the sample. A signal processing method that takes advantage of physical insight into the geometry and superposition is developed for identifying this edge reflection. Measurements are taken using a square and circular plate geometries. The data gathered is processed using both Kaiser windowing and the signal subtraction method developed in this research. Final results are presented with determinations made about how to optimize the method.