Non-destructive permittivity measurement of solid materials

Abstract

An open-coaxial probe suitable for measuring the permittivity of solid materials has been designed and tested. The peculiar structure of the probe allows an easy and firm contact with the surface of the material under measurement, resulting in highly reliable and reproducible dielectric measurements. The permittivity measurement is absolute, as the calibration procedure - based on a genetic algorithm - does not require the use of dielectric standards. The measurement system - including the probe, a network analyser, and the numerical code to determine the permittivity from reflection measurements - have been tested on solid materials of known properties, and used for determining the dielectric characteristics of several types of wood.

A multiresonance method for measuring the reflection coefficient in a waveguide

“…is performed in (3). PONOMARENKO, POPOV application of (5) is within 0.3 MHz for the resonance frequencies and 0.4 MHz for the peak widths at frequencies of 8-12 GHz.…”

“…Measurements of the reflection coefficient ( R ) in waveguides are necessary in studies of the dispersion of the permittivity and permeability of materials at microwave frequencies, in the development of the passive and active elements of microwave circuits, and for other purposes [1][2][3].…”

Measuring the permittivity and permeability of lossy materials :

“…(141). This can be accomplished by measuring Tempty of the empty specimen holder, (143) and consequently the ratio of the filled to empty holder reflection coeflacient is Rasmussen [102], Powell and Rasmussen [103], and Goldfarb and Bussey [58] have all described various ferrite permeameter designs. The conductivity of metals can be measured H-k with a four-probe system using voltmeters.…”

Dielectric Properties of Glucose Solutions in the Millimeter-Wave Range and Control of Glucose Content in Blood

“…Usually (see, for example, [1]), one employs a sophisticated and expensive vector network analyzers and measures the modulus, 1j2, and phase, (/, of the reflection coefficient, R*=Ir2ei (o (1jp2 is the power reflection coefficient and i = J ). However the measurement of the phase of the reflection coefficient is a rather difficult problem, and the measurement error amounts to ± 5%.…”