Open-ended coaxial-line technique for the measurement of the microwave dielectric constant for low-loss solids and liquids

Abstract

A system which enables fast and reliable measurements of the dielectric constant over continuous microwave frequency ranges for both solid and liquid low-loss materials is described. The main thrust of this work is the application of the open-ended coaxial-line probe technique, which has been used previously for soft biological materials, to low-loss solid samples. Using the instrumentation and procedure presented here, the dielectric constant for low-loss solids can be measured absolutely to ±2%–3% with routine care. The uncertainty can be reduced by about a factor of 2 by averaging several measurements. It is also smaller for liquid samples. This application features the use of relatively simple and readily available microwave components. Also, it is shown that a simple empirical relationship can be used to obtain the bulk dielectric constant from samples of a material in the form of thin slabs. The experimental results which are presented here for kapton, Teflon, Corning glass No. 0211, soda lime glass, magnesium oxide, sapphire, silicon, alumina, and lanthanum aluminate, as well as carbon tetrachloride, compare favorably with existing literature values.

Broadband Dielectric Spectroscopy: A Powerful Tool for the Determination of Charge Transfer Mechanisms in Ion Conductors

“…For a brief overview of the dielectric analyzers commonly used to carry out the measurements and for a detailed technical description of their mode of operation, the reader is referred to the specialized literature [6,7,12,14,33,36,[60][61][62][63][64][65][66][67]. In the following sections, the experimental details of the geometry of the sample cells, calibration and measurement errors are briefly described.…”

“…From 10 À6 to 10 7 , time-domain spectrometers, frequency-response analyzers, or AC bridges are used, and the sample is treated as a parallel or serial circuit of an ideal capacitor and an ohmic resistor [6,7,[60][61][62][63][64][65][66][67]. In this case, the effects of the sample size and geometry on the electric field distribution are neglected.…”

Debye relaxation and 250 K anomaly in glass forming monohydroxy alcohols

“…Part of the results at the highest frequencies of 100 MHz -30 GHz was obtained by measuring the reflection coefficient of an open-ended coaxial line, which was directly immersed into the sample liquid, kept in a glass tube. 24,25 For this purpose, the Agilent "Dielectric Probe Kit" and an Agilent E8363B Network Analyzer were used. In addition, in the same region of 100 MHz -30 GHz coaxial transmission measurements using a Hewlett-Packard 8510 network analyzer were carried out.…”

Near-Field Microwave Microscopy of Materials Properties

“…The complex reflectivity R or transmission coefficient T is measured, and properties of the sample are deduced. The most common technique is to measure reflectivity from a coaxial transmission line terminated (possibly with an air gap) by the sample [26,27,28,29,30,31,32,33]. Variations include the use of waveguides [34,35], waveguides covered by a resonant slit [36,37] and microstrip lines [38] in reflection.…”