• Scheuermann, Alexander
• Bialkowski, Konstanty
• Mishra, Partha Narayan
• Grieve, Sam
• Bore, Thierry
• Wagner, Norman

Abstract

This paper reports the design, the calibration and the application of a multiple open-ended coaxial probe. The objective behind development of this new sensor is to characterize the spatial and temporal distribution of electromagnetic properties of materials in frequency domain (radio to microwave region). Complex permittivity has been computed from the measured scattering function based on a capacitance model. Each of the probes have been calibrated against measurements performed on reference materials air, deionized water and methanol, for which dielectric properties are well established. The quality of the calibration has been validated with measurement made on another reference liquid (ethylene glycol) by comparing with results from the literature. The new sensor has then been used to measure the temporal and spatial electromagnetic properties over the 50 MHz–3 GHz frequency range of a reference geomaterial (kaolin) during evaporative dewatering. For this material, spatial porosities and gravimetric moisture contents have been estimated based on an advanced mixture model from the measured complex permittivity. Finally, the results have been compared with the average moisture content values obtained from gravimetric measurements. This paper, therefore, underpins the development of robust monitoring systems based on EM methods to study the spatial distribution of state parameters during evaporative dewatering processes.

Topics

• impedance spectroscopy