Measuring Dielectric Constant in Highly Conductive Soils Based on Surface Reflection Coefficients

Time domain reflectometry (TDR) fails in soils with high electrical conductivities, because the attenuation of the signal eliminates the reflection from the end of the probe. This paper describes a new approach for determining dielectric constants in highly conductive soils using TDR measurements. It makes use of information contained in the reflection at the soil surface rather than the reflection at the end of the probe. A relationship between the reflection coefficients at the soil surface with the apparent dielectric constant of the soil was established theoretically. The apparent dielectric constant of the soil can be estimated from the surface reflection coefficient. Results indicate that the dielectric constant can be determined with reasonable accuracy by the proposed approach for soils with high electrical conductivities, where the conventional travel time analysis fails due to significant signal attenuation.