Potential Surface Improvements by Bump Removal for 64-m Antenna

The surface panels of the main reflector of the 64-m antenna are initially set at an elevation angle of 45 deg, where most tracking occurs, to ideally match a prescribed praboloid. As the antenna is rotated about the elevation axis, distortions are introduced at the surface panel's supporting nodes as well as at the main reflector backup structure by changes in the direction of the gravity forces relative to the reflector symmetric axis. Major bump displacements could be corrected by controlling the position of the surface panel corners using adjustable mechanical jacks that change in length with the antenna elevation angle. The analysis of two bump-removal configurations is presented and one unique adjustment mechanism is proposed. A gain recovery of 0.2 dB at X-band would be available if the reflector structure distortion rms were reduced from 0.63 mm (0.025 in.) to 0.15 mm (0.006 in.).