Impedance Sensor for Fluid Permittivity Measurements up to 20 GHz with Single-Liquid Calibration

摘要

This paper proposes a novel impedance sensor for permittivity measurements of fluids. The sensing part is electrically small and can thus be represented by a simple equivalent circuit model up to 20 GHz. This is a benefit of the impedance measurement approach for permittivity extraction. A two-step calibration procedure, consisting of a simple Thru-Reflect-Line (TRL) and a single-liquid calibration is applied here. Both simulation and experiments on a printed circuit board realization are carried out. They verify the concept and demonstrate its robustness against production tolerances. Further improvements for enhanced accuracy and widened frequency range are suggested. The miniaturization potential is investigated in simulation.