HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Thomas, A. M. Articles by Lim, H. M. Search for Related Content PubMed Articles by Thomas, A. M. Articles by Lim, H. M. GeoRef GeoRef Citation Agricola Articles by Thomas, A. M. Articles by Lim, H. M. Related Collections Soil Methods/Instrumentation Other Geophysical Methods Experiment Design

SOIL PHYSICS

Broadband Apparent Permittivity Measurement in Dispersive Soils Using Quarter-Wavelength Analysis

School of Engineering, Univ. of Birmingham, Edgbaston, Birmingham B15 2TT, UK

^* Corresponding author (andrewmarkthomas{at}yahoo.com).

Time-domain reflectometry (TDR) has, since the early 1980s, become a widely used and robust method for measuring the electromagnetic properties of soils. Although it allows use of relatively simple probes and measurement equipment that free users from complex analysis of small soil samples in the laboratory, it provides little information on the dispersive nature of fine-grained soils. Therefore, we developed a quarter-wavelength analysis (QWA) methodology that allows apparent permittivity spectra to be obtained for soils, while retaining the same range of cells and probes and the simplicity of data analysis associated with TDR. We tested the technique on clay soils across a wide water content range and found that it provided useful data for frequencies ranging from approximately 100 MHz to >1 GHz—the accuracy being considered no worse than two units of apparent permittivity. The results show that the methodology is capable of providing broadband dispersion data that give significantly greater detail on soil electromagnetic properties than can be expected from single-frequency TDR data. This has a number of important advantages including the potential to provide accurate water content measurements in clay soils, a means to extend TDR soil monitoring data, and the opportunity to validate research into the measurement frequency associated with simple TDR measurements and time- to frequency-domain inversions.

Abbreviations: QWA, quarter-wavelength analysis • TDR, time-domain reflectometry • VNA, vector network analyzer