Noise properties of Josephson point contacts at microwave frequencies

An experimental investigation of the noise properties of Josephson point contacts at a frequency of 8.6 GHz is carried out. The choice of this high frequency is explained, on the one hand, by the possibility of extending the intermediate-frequency-amplifier band above 1 GHz (thus raising the fluctuation sensitivity of superheterodyne radiometers based on the Josephson effect) and, on the other hand, by the existence of sensitive amplifiers (masers and parametric amplifiers) in the microwave range. The voltage range is indicated in the case of which the main contribution to noise is made by intrinsic Josephson oscillation of the contact. At U greater than 1 mV, fluctuations increase with increasing voltage on the contact.