Measurement of High Loss Dielectric Materials Using a Resonant Technique

Centeno, A. , Breeze, J.D., Alford, N.M.N. and Krupka, J. (2008) Measurement of High Loss Dielectric Materials Using a Resonant Technique. In: 22nd European Frequency and Time Forum (EFTF 2008), Toulouse, France, 23-25 Apr 2008,

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This paper will report on a technique that has been developed for the measurement of the dielectric loss of materials which have a relatively high loss tangent. The method used employs a composite resonator that consists of the material under test being placed in the centre of a low loss ceramic ring resonator. The important feature of this configuration is that the electric energy filling factor in the sample is significantly lowered. This has the desirable effect of reducing the contribution to the resonator Q-factor of the sample material which has a high loss compared to the ceramic ring resonator. This enables the measurement of dielectric loss tangents which are significantly larger than those that can be measured using a conventional technique, such as making a cylindrical dielectric resonator of the sample material. In this technique the choice of resonant mode is very important. The electrical energy filling factor must low enough to ensure a measurable Q factor but at the same time high enough to measure a detectable perturbation of the resonance. It is also important to know the electrical filling factor of the ring resonator, which is made of a well characterised ceramic material, and the Q-factor contribution of any conducting surfaces in the resonant structure such as cavity walls. The choice of resonant mode and the effects of the other components in the resonator are obtained by using Finite Difference Time Domain (FDTD) and Mode Matching modelling tools. Measurement of the loss tangent of high resistivity Silicon over temperature has already been carried out with this technique by employing a BZT ring resonator resonating at around 5GHz in the TE01? mode. The results are very promising with loss tangents being measured that are an order of magnitude higher than could be measurable using a more conventional resonant technique. The current focus of this work is the measurement of liquids at microwave and millimetre wavelengths using Alumina resonators. The eventual aim of this work is to use the composite resonator as a sensor for liquid identification and protein detection.

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Centeno, Dr Anthony
Authors: Centeno, A., Breeze, J.D., Alford, N.M.N., and Krupka, J.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
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