Planar resonant microwave cavities for the detection of Ca(NO3 )2, KNO3, and Mg(NO3 )2 concentrations

The measurement of the concentration of nitrates in different solutions is of interest in industrial and biomedical applications. Due to this, it is proposed to work with resonant structures manufactured with microstrip technology which were designed as dielectric permittivity sensors. These devices depend on changes in the dielectric properties of the medium, so they can detect variations in the concentration of nitrates. Depending on the dielectric properties of the sample, the electrical response will be such that changes in the response can be related to variations in the percentage content of nitrates in the measured solutions. The increase in the dissolution of calcium, magnesium and potassium nitrates in water shows a clear and notable change in the resonance frequency with which it is possible to identify the percentage level of dissolution in the samples.