3D printed coaxial microwave resonator sensor for dielectric measurements of liquid

Ali Musa Mohammed, Yi Wang, Michael J. Lancaster

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This paper presents a coaxial resonator for dielectric measurements of low and medium loss liquids at multiple resonance frequencies up to 8 GHz with the fundamental transverse electromagnetic (TEM) resonant mode at 2 GHz. The measurement is by filling the entire resonator cavity with the material under test and the permittivity of the material is readily extracted using simple equations. This technique provides an easy and accurate extraction method of dielectric properties without any analytical approximation and dedicated software algorithm as used in broadband open coaxial probes or the complex perturbation formula in resonator‐based methods. This significantly reduces the risk of systematic errors from the model approximation. The measured quality factor of the resonator is 2650 to 3500 depending on the resonant mode. This allows for the measurement of samples with loss tangents up to 0.05 (Acetone taken as a reference). The device was made by 3D printing and verified by measurements of several common solvents at all four resonance frequencies. The results obtained agree well with values reported in literature. Further measurements of crude oil samples were carried out and results confirmed with values obtained using other techniques.
Original languageEnglish
Pages (from-to)805-810
Number of pages6
JournalMicrowave and Optical Technology Letters
Issue number3
Early online date30 Sept 2020
Publication statusPublished - Mar 2021

Bibliographical note

This work was supported by Petroleum Technology Development Fund (PTDF) in Nigeria by providing the PhD scholarship to Mohammed, A. M.


  • 3D printing
  • coaxial resonators
  • liquids
  • permittivity
  • quality factor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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