Free-space microwave moisture content measurement of moist sand

Abstract

Dielectric models are used with permittivity measurements of material for translation from permittivity to moisture content. A dielectric model for pure sand was developed based on fundamental physical properties such as the permittivity and geometry of the host material particles, and the frequency dependent processes that determine the permittivity of water. The measurement of sand using the short-circuited reflection method is discussed included associated pre-processing as is the processing of the measured data to extract permittivity values. A system is derived to automate the selection of appropriate solution equation, time-gate position and generation of initial values for numerical inversion. Measured data in the 1 - 6 GHz frequency range for sand with various volumetric moisture contents is compared with the dielectric model.