We report, for the first time, a low-cost and robust homemade hollow coaxial cable Fabry-Pérot resonator (HCC-FPR) for measuring liquid dielectric constant. In the HCC design, the traditional dielectric insulating layer is replaced by air. A metal disk is welded onto the end of the HCC serving as a highly reflective reflector, and an open cavity is engineered on the HCC. After the open cavity is filled with the liquid analyte (e.g., water), the air-liquid interface acts as a highly reflective reflector due to large impedance mismatch. As a result, an HCC-FPR is formed by the two highly reflective reflectors, i.e., the air-liquid interface and the metal disk. We measured the room temperature dielectric constant for ethanol/water mixtures with different concentrations using this homemade HCC-FPR. Monitoring the evaporation of ethanol in ethanol/water mixtures was also conducted to demonstrate the ability of the sensor for continuously monitoring the change in dielectric constant. The results revealed that the HCC-FPR could be a promising evaporation rate detection platform with high performance. Due to its great advantages, such as high robustness, simple configuration, and ease of fabrication, the novel HCC-FPR based liquid dielectric constant sensor is believed to be of high interest in various fields.
C. Zhu et al., "A Hollow Coaxial Cable Fabry-Perot Resonator for Liquid Dielectric Constant Measurement," Review of Scientific Instruments, vol. 89, no. 4, American Institute of Physics (AIP), Apr 2018.
The definitive version is available at https://doi.org/10.1063/1.5021684
Electrical and Computer Engineering
University of Missouri Research Board
Keywords and Phrases
Coaxial cables; Dielectric materials; Dielectric properties of liquids; Ethanol; Evaporation; Liquids; Mixtures; Reflection; Resonators; Thermal variables measurement, Air liquid interfaces; Dielectric insulating layers; Ethanol/water mixtures; Evaporation rate; High robustness; Highly reflective; Impedance mismatch; Liquid dielectrics, Phase interfaces
International Standard Serial Number (ISSN)
Article - Journal
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