Abstract
Time-domain reflectometry (TDR) methods used for measuring the dielectric properties of materials mostly utilize step or needle electrical pulses of constant amplitudes and shapes. Our novel approach enables determining the dielectric relaxation time of a sample using the analysis of the amplitudes of reflected pulses of two widths, in addition to bulk dielectric permittivity and electrical conductivity commonly obtained by the TDR technique. The method was developed for various values of electrical conductivity and relaxation time using numerical simulations of a five-rod probe placed in a material with complex dielectric permittivity described by the Debye model with an added electrical conductivity term. The characterization of amplitudes of two pulses of selected widths was done with regard to the dielectric parameters of simulated materials. The required probe parameters were obtained solely from numerical simulations. Verification was performed for the probe placed in aqueous KCl solutions with 14 different electrical conductivity values. The determined relaxation time remained roughly constant and independent of electrical conductivity. The obtained electrical conductivity agreed with the reference values. Our results indicate that the relaxation time, dielectric permittivity and electrical conductivity of the tested solutions can be simultaneously determined using a simple analysis of the amplitude and reflection time of two needle pulses of different widths.
Highlights
The dielectric permittivity of materials is a complex value
The aim of this work is to verify the hypothesis that it is possible to simultaneously determine the dielectric permittivity, electrical conductivity σ and the relaxation time τ of the measured material based on the analysis of the time between the incident and reflected pulses and their amplitudes, provided that the initial Time-domain reflectometry (TDR) pulses are of different width
The present study focused on the influence of electrical conductivity and dielectric relaxation time
Summary
The dielectric permittivity of materials is a complex value. Electron and atomic polarizations occur in solids, whereas in polar liquids orientation polarization dominates. Electrical conductivity, induced by ionic conductivity, is found in liquids [1,2]. The additional phenomenon of polarization resulting from the interaction of solid and liquid particles depending on their volume fraction, chemical composition, dielectric properties of component mixtures, appears in porous bodies like mixtures of the abovementioned materials with air [3,4]. The complex dielectric permittivity (CDP) spectrum and its description with the selected model enables us to gain more knowledge about the physical and chemical properties of the tested materials [5,6], and can be used in assessing their quality [7,8].
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