A single mode microwave heating device which operates at 2.45 GHz was modified to simultaneously heat and characterize ceramic materials. The equivalent circuit derived by Marcuvitz 9 to model the ceramic rod in the waveguide was used in the formulation. Three crystal detectors on the impedance analyzer were used as a reflectometer to measure the reflection coefficient of the load, so that transmission line measurements can be automated. The measured reflection coefficient at different temperature is a function of the dielectric constant and loss tangent of the ceramic material. The Newton-Raphson method was successfully used to solve a nonlinear complex equation. By using this system, a 94 alumina rod was heated and characterized and experimental results are presented.
This article is from 'Ceramic Transactions. Volume 21. Proceedings of the Symposium on Microwave Theory and Application in Materials Processing Annual Meeting of the American Ceramic Society (23rd) Held in Cincinnati, Ohio on April 29 - May 3, 1991,' AD-A253 631, p251-259.