Evaluating a low-cost self-manufactured Coaxial Open-Ended Probe for the Measurement of the Complex Permittivity of Granular Media

The measurement of the dielectric properties on moist substances has been proven to provide valuable information on the estimation of water content. Furthermore, the dielectric frequency spectrum seems promising as a source of information for the indirect determination of other useful physico-chemical properties of porous media, such as in soils. Access to dielectric spectroscopy measurements is limited due to the high cost and quality of the equipment used. Here, we evaluate the performance of a low-cost, self-manufactured open-ended coaxial probe for the measurement of the complex permittivity in the 10 to 500 MHz frequency range. The experimental probe is compared with a commercial model for measuring the dielectric properties of reference liquids. The tested probe has been found to provide accurate and reliable measurements of the complex permittivity, according to the reference values from the literature, for 50 to 500 MHz.