Dielectric Spectroscopy of High Permittivity Thin Solids Using Open-Ended Coaxial Probes

Abstract

Open-ended coaxial probe (OCP), as a widely used conventional technique for dielectric spectroscopy in the microwave and millimeter-wave regime, suffers from two difficulties when applied to high-permittivity solids. They include high sensitivity to minute gaps between the probe and sample, and reflections from probe boundary when layered samples are measured. In this contribution, we present first a calibration algorithm that aims at measuring the effective air-gap between the probe and sample. The result of this algorithm is later used in the OCP measurement process to cover the effect of this airgap. Second, we introduce using a lossy platform below the thin sample to mitigate the inaccuracies caused by probe truncation. An exemplary high-permittivity thin sample is outlined and measured using both conventional and new algorithm, which demonstrates a considerable reduction in measurement error when the proposed procedure is followed.