Performance and design of steerable antenna feed assembly for X-band payloads

An X-band steerable antenna assembly was required as part of the antenna farm subsystem for the X-band payload equipment used on satellites like HISPASAT. The design chosen for this antenna assembly uses a single feed horn to illuminate a steerable offset parabolic reflector. This system produces a moveable spot beam which may be aimed towards any point on the Earth´s surface visible to the spacecraft. The steerable antenna feed assembly (SAFA) has to withstand the increased vibration requirements resulting from its position on top of the mast. The SAFA consists of a profiled corrugated horn, a polariser, an ortho-mode transducer, two waveguide runs, mechanical and electrical interfaces, thermal control hardware and an alignment cube. The actual alignment adjustment system was mounted between the SAFA and the mast. The paper describes the performance requirements, design, manufacture and test of this feed assembly