The Use of Extraterrestrial Radio Sources in the Measurement of Antenna Parameters

Extraterrestrial radio sources, whose emission characteristics (flux density, spectrum, angular size) and coordinates have been firmly established by careful observations, have application in the measurement of the effective area (aperture efficiency and gain) of an antenna and its radiation pattern. The radio-emission characteristics of the strong discrete (celestial) radio sources, of the sun, and of the moon are presented. Problems encountered when the sensitivity is insufficient for complete radiation pattern determination , when the width of the radio source is comparable to the beamwidth of the antenna, when the illumination of the antenna aperture varies with pointing direction, or when the techniques are extended (after determining the gain of the ground-based antenna) to the measurement of the effective radiated power from a satellite are discussed.