High loss liquids permittivity measurement using millimeter wave differential dielectrometer

The propagation of an electromagnetic wave in a dielectric rod placed in a high loss liquid was studied theoretically and experimentally. The characteristic equation for the structure under study was derived and analyzed. The attenuation and phase velocity of this wave in the presence of distilled water and a water-ethanol solution were measured. Owing to these data the real and imaginary parts of complex permittivity of high loss liquids under the test were determined. We have a good agreement between theoretical and experimental results. The differential dielectrometer based on studied wave was designed. Thus, the complex permittivity of high loss liquids with sufficiently high accuracy can be obtained. It is also possible to record a rather small difference between two similar liquids according to their dielectric properties.