MMA Memo #161

Receiver Noise Temperature, the Quantum Noise Limit, and the Role of the Zero-Point Fluctuations

A. R. Kerr [1], M. J. Feldman [2], S.-K. Pan [1]

September 10, 1996

Keywords: Noise temperature, quantum noise, zero-point fluctuations, Y-factor, SIS, mixer, heterodyne, receiver, millimeter wave, submillimeter wave, sensitivity, noise, single sideband, double sideband

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 temperatures of the hot and cold loads, Th and Tc (usually room temperature and liquid nitrogen), are converted into radiated power "temperatures" to deduce TR from Y. Only one of these methods is consistent with Tucker's quantum mixer theory and the constraints of Heisenberg's uncertainty principle.

[1] NRAO
[2] Rochester University

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Last modified: 09 December, 1999