Sixteenth-Mode Substrate-Integrated-Waveguide (SMSIW) Resonator for Dielectric Characterization of Liquid Mixtures

Abstract In this work, a new concept of planar resonator technique for measurement of liquid mixture permittivity is proposed, designed, and implemented using a Sixteen-Mode Substrate Integrated Waveguide (SMSIW) technology. To design the proposed sensor, the conventional SMSIW resonator is designed with an additional air hole on the open side, and then we add a mask from the bottom side to close the air hole, which we fill with liquid under test (LUT). The detection principle is based on the resonance perturbation method. This perturbation yields a shift in resonant frequency due to the permittivity variation of the LUT inside the hole. The proposed sensor has been simulated using the commercial electromagnetic simulator: Ansoft HFSS. The SMSIW sensor has been tested for water, methanol, and ethanol as examples of liquids and water-ethanol with different concentrations as a liquid mixture. In order to validate the simulated results of the proposed concept, the sensor prototype is designed, fabricated and tested. The sensor is simple in design and low cost, which may be applied for various industrial applications.