The measurement of moderate size reflector antennas using astronomical calibrators

Astronomical calibrators have been used for many years for the purpose of measuring large antennas. They have been used to characterise the gain, beamwidth, pointing errors, and radiation pattern. Their advantages include their constant availability, stable signal level, and of course their remoteness. An additional benefit is that they are free of charge. Their use has been restricted to large antennas mainly because of their low signal strength. Their apparent motion across the sky as the Earth rotates is another complication, although this can be turned into an advantage in certain circumstances, as discussed. Technical advances and cost reductions in low noise device technology and computer control systems have opened up the possibility of the use of astronomical calibrators in the measurement of dishes of more moderate size. The likely errors in gain measurement have been assessed for a range of dish sizes and a calibrator has been suggested for use with satellite communication ground station antennas