Assessing electrical properties of ceramic samples

Abstract

We present an overview of electromagnetic numerical techniques and measurement apparatus that have been used for assessing electrical properties of ceramic samples. The complex permittivity of the ceramics is typically the first electromagnetic property of interest. In the measurement approach that we use, ceramic samples, in the shape of pills with metalized faces, are placed in either a proprietary coaxial chamber or in an open fixture. The scattering parameter (reflection coefficient) is measured using a network analyzer. For the deembedding of the complex permittivity of a sample one needs precise electromagnetic simulations, including detailed models of the chamber or the open fixture. For lower and intermediate frequencies we use a numerical technique for electrostatic analysis, based on the method of moments with Galerkin testing. We create a database that is used afterwards for evaluation of the complex permittivity practically in real time. For higher frequencies, a full electrodynamic model of the chamber is developed with WIPL-D software. For all our deembedding techniques, we have also developed a detailed model of losses in the SMA coaxial connectors, which is essential for a precise evaluation of the imaginary part of the complex permittivity for low-loss dielectrics. We present results of several measurements in order to illustrate the used techniques.