Measurement of Electromagnetic Properties of Food Products and Liquids

In this paper, measurement results of electromagnetic properties of water and selected fruits and vegetables are presented. The applied method is based on a commercially available open-ended coaxial line operating at frequencies up to 27 GHz. Subsequently, a novel method dedicated to the characterization of liquids at frequencies substantially exceeding 27 GHz is proposed. The system is based on a vertically-oriented open-ended metal hollow waveguide, so that the liquid can be easily poured into and the corresponding reflection coefficient can be measured to determine unknown complex permittivity of the liquid.