A Circular Waveguide Sensor for Concentration Detection of Liquid Compounds

Concentration is an important index to measure the proportion of a component in the mixture, and different concentration ratios will produce different reactions. Therefore, concentration detection plays an important role in human life and industrial development. In recent years, the application of microwave technology in food, oil, medicine, pharmaceutical and other industries have been paid more and more attention. Microwave technology provides higher adaptability and flexibility at a relatively low cost than more complex chemical processes. In this paper, a microwave sensor based on circular waveguide for concentration measurements of liquid compounds was proposed. The measurement principle is that when the concentration of solution in the waveguide changes, the resonant frequency of the waveguide will change. Taking sodium chloride solution as an example, the relationship between the dielectric constant and its concentration was determined by measurement, the relationship between dielectric constant and the resonant frequency was established by ANSYS simulation. So, based on the established relationship, the sensor can accurately detect solution concentration.