Frequency Variation of the Intensity of Cosmic Radio Noise

Abstract

THE intensity of cosmic radio noise (as received on horizontal half-wave dipole antennæ one quarter wave-length above ground) has been measured at 25 Mc. and 110 Mc. by H. V. Cottony, W. Q. Crichlow, J. W. Herbstreit and J. R. Johler at the Central Radio Propagation Laboratory, National Bureau of Standards, using identical noise diode calibration methods. The use of similar antennæ on the two frequencies ensured that comparable weights would be given the cosmic radio noise arriving from various directions in space. Results of these measurements are shown in the accompanying graph in terms of an external noise factor ¹. Results are given on 110 Mc. for antennæ oriented both normal to and parallel to the geographic meridian. These have somewhat different diurnal patterns which compare favourably with the calculated patterns obtained when the cosmic radio noise intensity contours obtained by Reber², using highly directional antennæ, are appropriately integrated over the two broad directivity patterns of the dipole antennæ.