Extensive Modeling of a Coaxial Stub Resonator for Online Fingerprinting of Fluids

A straightforward method of extensive modeling of a lossy stub resonator system for online fingerprinting of fluids is presented in this paper. The proposed model solves the telegrapher's equations including the skin effect and dielectric losses and describes the amplitude versus frequency response of lossy coaxial stub resonators with a fluid under investigation as dielectric. The adequacy of the method is demonstrated by comparing simulations with experimentally obtained data. Even though we applied the model to a coaxial stub resonator for the online fingerprinting of fluids (e.g., for water quality monitoring), the potential applicability of the method reaches further. Indeed, the method introduced here may be useful for different types of sensors based on lossy transmission line theor

On-line fingerprinting of fluids using coaxial stub resonator technology

Here we demonstrate the proof-of-principle of a coaxial stub resonator to assess the dielectric properties of fluids. This radio-frequency spectroscopy method is based on coaxial stub technology and comprises quarter wave length open-ended resonators that are filled with a liquid sample as dielectric between inner and outer conductor. Changes in the dielectric properties of the liquid sample result in changes in the electric properties of the resonator, e.g., its resonance frequency and quality factor. In addition to a batch resonator, results obtained with a flow-through resonator indicate that the concept can be further developed into a cost-efficient and low-maintenance sensor for the on-line fingerprinting of the dielectric properties of fluids, such as drinking or waste water. ethanol and glycerol