Liquids Permittivity Measurement Using Two-Wire Transmission Line Sensor

A novel method for the measurement of complex permittivity of liquid dielectric materials in a wide frequency range is proposed. The technique utilizes an open-ended two-wire transmission line sensor that is submerged in a liquid-under-test to determine its complex permittivity from the measured differential reflection coefficient. The proposed approach has been theoretically analyzed to derive the appropriate sensor's model and the required calibration procedure as well as experimentally validated by measurements of three liquids having frequency-dependent complex permittivity. Moreover, measurement accuracy analysis has been provided, including the method`s uncertainty estimation and error sources' discussion. Finally, the measured permittivity of each liquid has been compared against tabularized data. Good agreement has been obtained proving the validity and applicability of the proposed method.