Simulation of time domain reflectometry based on soil dielectric properties
Abstract
The purpose of this study was to establish a solid theoretical model for the method of Time Domain Reflectometry (TDR), based on dielectric properties of the materials under test, and accurately simulate the TDR waveforms for different materials, including soils. A multi-section coaxial transmission line model was proposed, which incorporates a complete path of electromagnetic wave propagation in the TDR measurement system. A classic dielectric theory (Debye's molecular polarization and Cole-Cole's modification) was used to describe the dielectric properties of materials. The parameters of the measurement system were obtained by using an optimization process. The simulated TDR waveforms displayed good matching with the actual waveforms, for materials with known dielectric properties, showing that this model is adequate. This model was further applied to study the material dielectric properties of soils by inverse calculation of the material parameters. An experiment was designed to measure the dielectric permittivities of 150 Specimens of 11 different soils, using a network analyzer. The dielectric permittivities of those Specimens were also calculated from the TDR waveforms recorded in the same test. The comparison between the calculated and measured results showed good consistency for some Specimens, with the same varying trend, and close values. The calculated results were further analyzed to reveal the dielectric characterizations of different soils. The study found that it is highly possible to discover the correlation between some material parameters and the soil state, including water content and density, leading to more accurate and more convenient TDR measurement.
Degree
Ph.D.
Advisors
Deschamps, Purdue University.
Subject Area
Civil engineering|Soil sciences
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