Improved microwave Michelson interferometer operating at 140 GHz

Several major improvements have been made to a Michelson-type microwave interferometer operating at a frequency of 140 GHz. An enlarged dielectric cell, an improved measuring system, and a highly stable microwave system allow a precise determination of the complex dielectric constant for low-loss liquids. The effect of a mismatch in the microwave system is discussed and the computed behavior of the instrument is compared to that found experimentally. An experimental technique is described which takes account of the effect. Some results are presented for various solutions of nitrobenzene in benzene and for the alkane series of hydrocarbons. The values obtained are compared with values reported by other workers using different methods.