The 64-m Antenna Automatic Subreflector Focusing Controller

Abstract

Defocussing of the radio frequency beam arises from gravity-induced structural deformations as the 64 m Deep Space Network antenna rotates about the elevation axis. The subreflector controller generates the axial (z) and lateral (y) offset corrections necessary to move the subreflector, thus minimizing the gain losses due to this defocussing. The technique used to determine these offset errors is discussed, and a description of the new subreflector controller is presented.