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.


Electrical and Computer Engineering

Research Center/Lab(s)

Intelligent Systems Center


University of Missouri Research Board


The work was supported by 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)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2018 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Apr 2018