Dielectric properties measurement methods for solids of high permittivities under microwave frequencies and between 20 and 250 °C
Abstract
This article presents and discusses the results of a dielectric properties measurement intercomparison on a ceramic material, in the microwave frequency region from 500 MHz to 20 GHz and at variable temperatures from 20 °C to 250 °C. The same ceramic samples have rigorously been tested using three different techniques: a reflection method using a coaxial probe coupled to a network analyzer and two types of resonant cavities techniques (cylindrical and rectangular). This study highlights the advantages and drawbacks of each technique and demonstrates that the real part ε’r and the imaginary part ε”r of the permittivity can be advantageously and separately determined by using different shapes and volumes of samples. In addition to dielectric properties, valuable informations about the surface state of the material can also be obtained. Finally, it is shown that combining the different methods can be a benefic and a clever way to obtain very accurate results in a wide range of temperature or frequencies.