ACTIVE QUASI-OPTICAL REFRACTOMETER IN THE EXTREMELY HIGH FREQUENCIES (EHF) BAND

A precision EHF band refractometer used for measuring small variations of permittivity and/or permeability of substances, including gases, is suggested and tested. The basis of the method and the device is formed by the interrelation between the quasi-optical Gunn oscillator frequency and dielectric and magnetic constants of the sample placed into the high-Q open resonance system of the oscillator. Description of the suggested thermally compensated quasi-optical generator with a low level of noise is given and its characteristics are provided. A cuvette for investigation of powdery substances is designed, and the results of numerical modeling of the open resonator with a cuvette are provided. Estimation of the threshold sensitivity of the measuring system to small variations of the refraction factor is performed.