A vector network analyzer combined with an open ended coaxial probe provides a way to make non-destructive measurements of complex permittivity. These measurements can be made on both solids and liquids.
Many authors have done work on using an open ended coaxial line for making these measurements. They have presented different techniques for modelling the coaxial probe. This paper does not focus on the area of modelling, but deals instead with the use of a vector network analyzer and coaxial probe in making measurements. To enhance measurement accuracy, the technique described adapts a calibration technique currently in use in vector network analysis.
An HP 8720B vector network analyzer was used for the development and measurements presented in this paper.