Dielectric properties measurements under microwave heating (IEEE MTT, 2015)

Explore the remarkable advancement in permittivity characterization of materials featured in our paper, “Dynamic measurement of dielectric properties of materials at high temperature during microwave heating in a dual mode cylindrical cavity,” published in July 2015 in IEEE Transactions on Microwave Theory and Techniques.

This paper presents a new system developed at the ITACA-DIMAS laboratory. It consists of a new microwave cavity and heating system for microwave processing and in situ dynamic measurements of the complex permittivity of dielectric materials at high temperatures (around 1000 ºC).

The method is based on a dual-mode cylindrical cavity where heating and testing are performed by two different swept frequency microwave sources and a cross-coupling filter isolating the signals from both sources.

By adjusting the frequency bandwidth of the heating source and the level of coupling to the cavity, an automatic procedure allows for the establishment of a desirable level of heating rate to the dielectric sample to reach high temperatures in short cycles.

This system provides the dielectric properties of materials as a function of temperature by an improved cavity perturbation method, with an accuracy of the complex permittivity better than 5% with respect to a rigorous analysis (full wave method) of the cavity.

The functionality of the microwave dielectric measurement system has been demonstrated by heating and measuring glass and ceramic samples up to 1000 C.