Open-Ended Coaxial Probe: Model Limitations

We propose a procedure to determine the validity range of any empirical model of the open-ended coaxial probe transition that is used to measure the permittivity of materials. The procedure is illustrated by an application of the method to a standard coaxial cable probe, a permittivity range of interest in the food industry and, as an empirical model, the well-known "lumped capacitor model".