A microwave performance calibration system for NASA´s Deep Space Network antennas. 1. Assessment of antenna gain and pointing, and calibration of radio sources

The NASA JPL Deep Space Network (DSN) of large, dual reflector, Earth-based antennas is subject to continuing demands for improved performance, performance evaluation, and reliability as a result of communications, control, and radio science requirements for future missions. As a consequence, a new generation of 34-m beam waveguide (BWG) antennas is being added to the existing complement of 34-m and 70-m cassegrain-like antennas (shaped reflectors), and X-band (8.42 GHz) and K_a-band (32 GHz) transmitting and receiving systems. The latter utilizing stable, total power radiometers (TPRs), are being implemented throughout the network to complement the existing S-X-band capability. These developments have in turn established the need for a set of easy to use and reliable tools for the assessment, calibration, and improvement of the performance of a large number of antenna systems. In this paper we describe a new approach being taken for the measurement of antenna gain and pointing, as well as the calibration of radio sources used in the antenna gain assessment