RECEIVER NOISE TEMPERATURE, THE QUANTUM NOISE LIMIT, AND THE ROLE OF THE ZERO-POINT FLUCTUATIONS

Abstract

There are in use at present three different ways of deducing the receiver noise temperature TR from the measured Y-factor, each resulting in a different value of TR . The methods differ in the way the physical of the hot and cold loads, T h and Tc (usually room temperature and liquid nitrogen), are converted into radiated power temperatures to deduce T R from Y. Only one of these methods is consistent with Tucker's quantum mixer theory and the constraints of Heisenberg's uncertainty principle. The paper also examines the minimum system noise achievable with single- and double-sideband receivers.