A new automated waveguide system for the precise measurement of complex permittivity of low-to-high-loss liquids at microwave frequencies

An automated measuring system is described which enables the complex microwave permittivity of liquids to be determined at particular frequencies. A special cell design offers the possibility of precisely measuring a range of liquids from low to high loss. Constructional details of the sample cell are presented together with a system diagram of the microwave apparatus and a description of the analysis of primary data. Possible experimental errors are considered and results for measurements in the XN- and Ku-waveguide bands (5.3-8.4 and 12.5-18 GHz) are discussed.