Some calculation methods and universal diagrams for measurement of dielectric constants using open-ended coaxial probes

Several formulas for the calculation of the admittance of open-ended coaxial probes from the complex permittivity, ε, of the measured medium and the dimensions of the probe are presented. The inverse problem, calculation of ε from the measured admittance of the probe, is also studied in detail. These formulas are discussed and compared in terms of numerical calculations. New universal diagrams of solutions of these problems are presented which are both convenient and useful for practical measurements. Some distinguishing features of the relationship between ε of the measured medium and the admittance of the probe are discussed