An all-dielectric microwave absorber composed of a dielectric hollow cylinder filled by chemical liquids and its application on sensing

Karacan N., EKMEKÇİ E.

SENSORS AND ACTUATORS A-PHYSICAL, vol.314, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 314
  • Publication Date: 2020
  • Doi Number: 10.1016/j.sna.2020.112235


In this study, design, characterization and sensing application of an all-dielectric absorber are studied in microwave S-band. In the design, the unit-cell is composed of a cylindrical dielectric container (CDC), a cylindrical dielectric resonator (CDR) and a dielectric substrate as the support material. For an important part of the study, except the parametrical analyses, the CDR is formed by specially selected chemical liquids (CLs) separately. The study consists of three main stages. In the first stage, several analytical analyses take part for the determination of the CDR dimensions (i.e., height and the radius) regarding the microwave rectangular waveguide medium. In the second stage, some specific numerical analyses have been performed to reveal the dependence of the absorption spectra on relative permittivity and loss tangent of CDR and also to explain the resonance mechanism considering the electric and the magnetic field distributions inside the structure. This stage is important to demonstrate that electric and magnetic dipole resonances are merged at a common frequency which results in a stronger absorption peak. In the final stage, a sensing application is presented. On this aim, the CDC has been filled by three selected CLs (i.e., acetone, acetonitrile and ethyl methyl ketone) separately and the changes in the absorption spectra have been presented both in simulations and experiments. The numerical and the experimental results reveal that the location of the absorption peak decreases effectively with the increase of the relative permittivity of the CL and the absorption band gets broader as the loss tangent of the CL gets higher. These results reveal that obtaining a relatively narrow band of absorption and controlling the absorption spectrum is possible in microwave all-dielectric designs by an engineered choice of the CL as the CDR material. This approach may not only be used for concentration sensing of chemical solutions but also for tuning the absorption spectrum in magnitude or in frequency by controlling the CDR (i.e., CL inside the CDC). (C) 2020 Elsevier B.V. All rights reserved.