The influence of natural noise upon antenna system performance

The effects of natural radio noise upon the performance of ground antenna systems are examined. After the spatial and spectral properties of some major sources of radio noise are described, the results of a comprehensive program of machine computation of antenna temperature are analyzed. These results and those of a recently completed noise measurement program are used to evaluate the carrier-to-noise ratio (c/n) at ground receiving antennas tracking a space probe and a medium-altitude satellite. From published maps of galactic brightness temperature, from flux-density spectra developed with data on thermal and nonthermal radiation from the planets, and from recent models of the solar atmosphere, antenna temperatures have been computed for apertures ranging from 30 to 1,000 feet at frequencies between 60 and 30,000 mc (megacycles).