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4th International Symposium on Sensor Science (I3S2015): Conference Report
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Sensors 2016, 16(2), 191; doi:10.3390/s16020191

A Time-Domain Reflectometry Method with Variable Needle Pulse Width for Measuring the Dielectric Properties of Materials

Bohdan Dobrzański Institute of Agrophysics of the Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
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Academic Editor: Hans Peter Lang
Received: 2 November 2015 / Revised: 20 January 2016 / Accepted: 29 January 2016 / Published: 4 February 2016
(This article belongs to the Special Issue I3S 2015 Selected Papers)
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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. View Full-Text
Keywords: time-domain reflectometry (TDR); dielectric permittivity; relaxation time; Debye model; FDTD simulations time-domain reflectometry (TDR); dielectric permittivity; relaxation time; Debye model; FDTD simulations
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Wilczek, A.; Szypłowska, A.; Kafarski, M.; Skierucha, W. A Time-Domain Reflectometry Method with Variable Needle Pulse Width for Measuring the Dielectric Properties of Materials. Sensors 2016, 16, 191.

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