Measurement of Radio Sources at Centimetre Wave-lengths

Abstract

IN future, the limit of detection of faint radio sources, at wave-lengths of 10 cm and less, is likely to be set by the radiation from water vapour and rain in the troposphere^1,2. The dominant factor is the minute-to-minute fluctuations in received power, which may be as much as 2° K at λ 3.7 cm. These fluctuations are greatly in excess of the receiver noise fluctuations, and may destroy all the benefit of using a modern low-noise amplifier such as a maser.