Dielectric spectroscopy at microwave frequencies

A dielectric spectrometer operating continuously over the frequency range of 0.01 to 18 GHz is described. The frequency dependence of both the attenuation coefficient and the permittivity of liquids may be measured over this frequency range to an estimated uncertainty of better than +or-5% when alpha d>1 ( alpha is the attenuation coefficient of the liquid and d the depth of liquid in the cell). Significant measurements are still possible with reduced accuracy when alpha d<1. The method is capable of fast routine operation with the dielectric absorption process characterized in about one hour. This sweep-frequency method is capable of a higher accuracy than the time-domain spectrometer and may be adapted to give a direct display of the frequency variation of the attenuation.