Cell size for water content-dielectric constant calibrations for time domain reflectometry
Suwansawat S, Benson CH
(Received 27 February 1998; accepted 13 August 1998)

Abstract
Time domain reflectometry (TDR) is a nondestructive electromagnetic technique used to measure the volumetric water content of soil. A key component of the method is the calibration equation relating the apparent dielectric constant (K_a) to the volumetric water content (q). In this study, tests were conducted to evaluate dimensional requirements for a TDR calibration cell. The results show that a PVC cylinder having the same dimensions as a standard compaction mold (diameter = 102 mm, height = 116 mm) is a suitable calibration cell for two-rod TDR probes having diameter = 4 mm, center-to-center spacing = 30 mm, and length = 80 mm. The cell can also be used for three-rod probes having the same dimensions as the two-rod probe, and a center-to-center rod spacing of 20 mm. Calibrations made with this small cell are essentially identical to calibrations made in a much larger cell where boundaries are unlikely to be important.

Keywords:
calibrations, cell size, reflectometry, soils, time series methods, water content

Paper ID: Ch1X3X12

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Author Suwansawat S, Benson CH Title Cell size for water content-dielectric constant calibrations for time domain reflectometry Symposium , Committee on