Analytical method to estimate the complex permittivity of oil samples

Lijuan Su, Javier Mata-Contreras, Paris Vélez, Armando Fernández-Prieto, Ferran Martín

Research output: Contribution to journalArticleResearchpeer-review

100 Citations (Scopus)


© 2018 by the authors. Licensee MDPI, Basel, Switzerland. In this paper, an analytical method to estimate the complex dielectric constant of liquids is presented. The method is based on the measurement of the transmission coefficient in an embedded microstrip line loaded with a complementary split ring resonator (CSRR), which is etched in the ground plane. From this response, the dielectric constant and loss tangent of the liquid under test (LUT) can be extracted, provided that the CSRR is surrounded by such LUT, and the liquid level extends beyond the region where the electromagnetic fields generated by the CSRR are present. For that purpose, a liquid container acting as a pool is added to the structure. The main advantage of this method, which is validated from the measurement of the complex dielectric constant of olive and castor oil, is that reference samples for calibration are not required.
Original languageEnglish
Article number984
Issue number4
Publication statusPublished - 1 Apr 2018


  • Complementary split ring resonator (CSRR)
  • Complex dielectric constant
  • Complex permittivity measurements
  • Microstrip technology
  • Microwave sensors


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