Dynamic High Temperature Microwave Complex Permittivity Measurements on Samples Heated Via Microwave Absorption*

Abstract

A new dynamic method for measuring the dielectric constant and the dielectric loss tangent (tan 8), of spherical or rod shaped test samples at either low (below 0°C) or high temperatures (1500°C) is described. Experimental results for glass-bonded mica (Mycalex), steatite ceramic (Centralab type 302), borosilicate glass (Corning 7740), and Iron sulfide (FeS) are given for temperatures varying from room temperature up to 600°C. The test samples are heated by microwave energy inside a cavity resonator which has two dominant modes. One of these resonances is used for heating the sample at the ISM frequency of 2.45 GHz whereas the second resonance is used for measuring the dielectric properties. Cavity test cells suitable for either spherical or rod shaped samples are described. The experimental results obtained are in general agreement with results published in the literature.