Electrode System for Dielectric Property Measurements in a Wide Frequency Range

Abstract

A two-terminal micrometer electrode system of 30mm diameter for the rapid and easy measurements of dielectric constant and dissipation factor over a wide frequency range from 1kHz to 100MHz is presented.
To minimize the error in the measurements of dielectric constant and dissipation factor caused by the uncertainty of the specimen's mean thickness determination, a specimen's mean thickness measuring mechanism is introduced to the electrode system having a shield ring, which was developed for the measurement of the solid plate specimen of less than 1.5mm thickness. To improve the sensitivity of the loss measurement at high frequencies around 100MHz and the stability of the electrode's Q at low frequencies around 1kHz, guarded variable capacitance diodes have taken place of a variable air capacitor which is in parallel with the electrode and is used to establish the resonance at any arbitrary electrode gap length. When the half-power varying-gap method which was developed by the authors is used, specimens having a mean thickness 0.5-1.5mm can be measured within about ±0.2% for the dielectric constant and about ±3% for the dissipation factor over the frequency range from 1kHz to 100MHz.