PCB rectangular patch antenna and monopole antenna based multipurpose liquid sensor applications

In this study, two sensor structures based on a PCB (Printed Circuit Board) microstrip monopole antenna with working frequency of f=2 GHz and a PCB microstrip rectangular patch antenna with the working frequency of f=4.656 GHz were designed in order to determine the ethanol alcohol ratio in wine and isopropyl alcohol ratio in sanitizers. Both sensors were able to determine the ethanol alcohol content in the wine and the isopropyl alcohol content in the sanitizer through the return loss values. When designing the monopole antenna and patch antenna, the electromagnetic permittivity ratios of the samples corresponding to the alcohol ratio and isopropyl ratio are considered and the antenna dimensions along with the working frequency were optimized. In the related frequency band, permittivity values corresponding to the ethanol alcohol and isopropyl alcohol ratios exhibit a linear change and make the sensor design possible. While performing the measurement with monopole antenna, the radiating part of the antenna was thought to be immersed in the samples and the test setup was optimized on this. In the patch antenna, the mixtures were poured in small amounts into the rectangular chamber structure defined by the antenna size and the results were obtained. According to the obtained results, it was found that the changes in the resonance frequency can be associated with ethanol alcohol and isopropyl alcohol ratio inside the smaples. The change of ethanol alcohol amount and isopropyl alcohol in the samples tested at the resonance frequency for monopole and patch antenna is proportional to the change in the resonance frequency and they are very close to a characteristic close to linear. With this feature of the sensors, it is seen that it allows determining the percentages of the mixtures. The loss tangent values and dielectric constants of the samples used in the study were obtained with KEYSIGHT brand PNA-L N5234A Network Analyzer that can operate at the frequencies up to 43.5 GHz and the dielectric probe compatible with this device. Simulation of the targeted sensor structures in the computer environment were conducted in an electromagnetic simulation program based on Finite Integration Method (FIT). Both sensors have low cost and high sensitivity. In addition, they have small structure that can be integrated which can also be counted as another advantage of the design.