Non-Invasive Dielectric Characterization of Chemical Solvents using Microstrip-Fed Dielectric Resonator based Sensor

This paper presents a square ring dielectric resonator (DR) based sensor for non-invasive characterization of the liquids. The DR is excited in TE $\text { TE } _ { \delta 11 } ^ { x }$ mode using a conformal strip connected to microstrip line. The technique is based on the perturbation theory in which a hollow cylindrical core is made in the DR to hold the liquid test specimen. The proposed sensor system is simulated using the frequency domain solver of CST Microwave Studio for wide range of dielectric constant of the test specimens and an empirical relationship between the dielectric constant and shift in the resonant frequency is proposed. The proposed sensor is simple and doest not require any external sample holder to place the liquids. Moreover, the sensor shows the appreciable sensitivity of 50 MHz, which is more than the earlier reported DR based sensors. It is found that the proposed sensor gives a maximum of 2% error in the extracted value of the dielectric constant of various chemical solvents.