Microwave Measurement of the Degree of Binding of Water Absorbed in Soils

Abstract

The variation of the relative permittivity and ioss tangent of soil-water mixtures with change in moisture content has beeri measured at a wavelength of 2.8 centimetres. Sand, Ottawa sand and Gypsum are used as the soil samples. The experimental results are interpreted in terms of Wiener’s theory of dielectric mixtures. It is shown that changes in the ‘mixing condition’ may be used to indicate changes in the degree of binding of the absorbed water. The plane wave bridge technique used for the measurements is described in detail. Based on the above technique, a scheme for the continuous, non-contact measurement of moisture in granular materials is also described and briefly discussed.