Microwave sensor for accurate measurements of water solution concentrations

The paper presents results of sensitivity estimations of the microwave sensor designed for controlling concentration of various mixture solutions. It consists of the resonator supporting TM₀₁₀ mode with the axial glass tube filled with the solution under test. Concentrations of both organic (sugar, alcohol) and inorganic (NaCl, KMnO₄ ) water solutions were determined with high accuracy. The sensitivity of the sensor in determination of NaCl is 0.4 dB/(mg/ml) within the concentration range 0 - 1 %. It is about the two orders higher than sensitivity of the sensor based on near field dielectric resonator.