Liquid-based dielectric resonator antenna and its application for measuring liquid real permittivities

In this study, a water-based rectangular dielectric resonator antenna is designed and analysed. The compactness of the antenna because of the high relative permittivity of water is demonstrated in both simulation and experiment. In addition, a dielectric resonator antenna-based technique is proposed for measuring liquid permittivities. The resonance frequencies of the antennas with fixed configurations are obtained from finite-element electromagnetic (EM) simulation for liquids with different permittivity values. An analytical model of liquid permittivity as a function of the antenna resonance frequency is then developed. Based on this predictive model, the measurement of the liquid real relative permittivity can be easily achieved by measuring the antenna resonance frequency. The measured permittivity values of distilled water and 10% glucose solution are in agreement with previous data in the literature, demonstrating the effectiveness of the proposed liquid permittivity measurement technique.