VNA Instrumental Phase Error Influence on the Calculation Accuracy of the Dielectric Permittivity

To determine the dielectric permittivity, there are many methods, one of which is phase. This method is based on the measurement of phase characteristics that can be obtained from s-parameters. In this paper, an analysis of the influence of instrumental error on the accuracy of measuring the effective dielectric permittivity of the measured object was carried out. As a result, an expression was obtained for a quick estimate of the error of the effective dielectric permittivity, which can be used to determine the required line length at a known maximum permissible measurement error at a given frequency. It is determined that it is most optimal to use a microstrip transmission line for the implementation of measuring equipment. The reasons are a small measurement error compared to other types of lines, high manufacturability and low material costs in the implementation of measuring equipment. The experiments conducted using the differential phase method showed that the data fit into the range of errors, which indicates the correctness of the expressions and conclusions obtained in this work.