Time Domain Calibration Method of Open-Ended Coaxial Probe in Dielectric Measurement

The dielectric method by open-ended coaxial probe owns the advantages of simple structure and nondestructiveness. It is widely applied in the dielectric measurement of liquid solutions and semisolid mediums. Noticeably, the calibration directly affects the accuracy of the measurement. In order to solve the problem of complicated operation and the difficulty in preparation by the traditional three-load calibration method, this article conducts the error model analysis based on the scattering parameter matrix and proposes a time-domain calibration method. Under time-domain conditions, this method only needs one open-circuit load to extract three calibration error parameters through time window gating. The reliability of the time-domain calibration method is verified by simulative comparison, comparison of the measured complex permittivity of absolute ethanol solution with the theoretical value, and comparison of sodium chloride solution’s complex permittivity with the results of three-load calibration. The consistency of these three comparison results shows that the new method can provide technical support for the dielectric measurement by an open-ended coaxial probe.