This review covers approximately 15 years of development in the techniques used to measure dielectric properties of materials over the frequency range 1 MHz to 1500 GHz. An introductory section summarizes the broad development trends and is followed by short sections which deal with developments at a more detailed level. The approaches described include time- and frequency-domain methods; reflection, transmission, and resonant methods, guided and free-space methods; discrete-frequency and broad-band methods, especially Fourier Transform Spectroscopy. Measurements on magnetic materials are also briefly discussed.

The measurement of the properties of materials

Two approaches due to the complex frequency and to the perturbation theory are described to compute accurately the Q-factors of the circularly-symmetric TEO modes for dielectric rod resonators placed between two parallel conductor plates and in a conductor cavity. These techniques allow us to estimate separately the Q-factors due to radiation, conductor, and dielectric losses from only the computation of resonant frequencies by means of the mode-matching method. Validity of the theories is verified by experiments. The influence of the conductor shields on the Q-factors is discussed from the computed results. A possibility of realizing high-Q dielectric resonators is suggested.

Influence of Conductor Shields on the Q-Factors of a TE /sub 0/ Dielectric Resonator

An effective dielectric constant technique to determine the resonant frequency of the TE/sub 01 delta / mode of a cylindrical dielectric resonator placed in a microwave integrated circuit (MIC) environment is discussed. An expression for the dielectric constant epsilon /sub eff/ which makes it possible to obtain results that compare favorably with rigorous methods is given. Experimental results demonstrating the method's validity are also reported. For a given resonant frequency, closed-form expressions for computing the height of the resonator are given. >

Resonant frequency of cylindrical dielectric resonator placed in an MIC environment

In this paper, dielectric resonators possessing separable-coordinate geometries immersed in planarly-inhomogeneous media are analyzed using a volume electric-field integral-equation (IE)/Galerkin's technique. A three-dimensional complete entire-domain basis function set is utilized in numerically solving the IE. It is shown that a few terms of one physically significant subset of basis functions are usually sufficient for the accurate determination of complex resonant frequencies of cylindrical and rectangular resonators immersed in homogeneous and planarly inhomogeneous environments. The results using a few basis functions show good agreement with the previous literature, and new results are presented for some rectangular resonator geometries.

An efficient full-wave method for analysis of dielectric resonators possessing separable geometries immersed in inhomogeneous environments

The unloaded Q-factor of a dielectric resonator is degraded due to conductor loss when it is placed in an MIC environment. The authors report approximate but quite accurate closed form expressions for the Q-factor due to conductor loss. The results obtained are in good agreement with those of rigorous numerical methods. The effect of geometrical parameters on the useful tuning range of the structure is studied. Finally, an explicit relationship between the resonant frequency sensitivity factors and the conductor Q-factor is derived. >

Accurate conductor Q-factor of dielectric resonator placed in an MIC environment

A cylindrical dielectric resonator placed on microstrip line is used for measuring the complex permittivity of microwave low-loss high epsilon/sub r/ dielectric materials. The method is based on the accurate solution of this resonator with TE/sub 01delta/ mode and is compared to the method of dielectric rod resonator with TE/sub 11/ mode. The accuracy of the both method is similar - the measurement accuraoy of relative dielectric constant is better than 0.2 percent and measurement accuracy of loss tangent is about 1·10/sup -4/.

Sz. Maj

Papers

Application of a Dielectric Resonator on Microstrip Line for a Measurement of Complex Permittivity