A deformable subreflector for the Haystack radio-telescope

The authors describe the design of a subreflector which can be deformed to compensate for gravity and thermal deformations of the primary reflector. The design allows optimal positioning of the deformable subreflector for maximum gain. It also shows deformation of its skin to compensate for gravity sag of primary reflector panels as well as the astigmatic deformation of subreflector to compensate for part of the gravity and thermal deformation of the backstructure. This deformable subreflector was developed to compensate for gravity-induced deformations of the primary reflector of a 120-ft-diameter antenna to allow it to operate at up to 100+ GHz. The performance of the subreflector was verified by analysis, and a test program used to ensure the adequacy with respect to strength. The deformable subreflector is expected to reduce the gravity-induced deformations of the primary reflector by about 70 to 80%.<>