Photogrammetric determination of the form of a 10m diameter antenna

The application of photogrammetry to the determination of the form of a 10-m-diameter Cassegrain antenna used for precise satellite time transfer work is discussed. The objective of the study reported here was to confirm the profile of the main reflector both for operation in the design bands of 4/5 GHz and also for the possible use of the antenna in the bands 12/14 GHz if the manufacturing tolerance of 1 mm was sufficiently well maintained over the central part of the surface. Results of plate measurements, taken at about 450 points, show departures of 2-3 mm from the design surface and gravitational distortions of several millimeters.