Description:
<jats:p>For the special case of determining the dielectric loss factor of liquids of very low loss (tanδ about 10−4) at centimeter wavelengths, an improved interferometer method using standard waveguide components has been developed. One interferometer operating at frequencies of about 9 GHz is described in detail. The influence of multiple reflections and of wall losses on the accuracy of measurement is investigated. The uncertainty in tanδ is less than 1.2×10−5. Measurements by a second interferometer at 29 GHz coincide well with values obtained by known cavity resonator methods.</jats:p>