Precision enhancement in 8 mm interferometry

A Q band interferometer for determining the complex permittivity of materials having dielectric loss factor within 10^–3 to 1, has been developed. The technique involves the use of a computer-assisted digital voltmeter for data acquisition and treatment. The method of computing the dielectric parameters from the deduced VSWR and minima displacement is outlined and precision increase with this type of measurement is discussed. Results for polar solutes in non polar and in polar solvants are presented. Measurements on solids within the temperature range 20–400°C are also discussed in conclusion.