Antenna Pointing Mechanisms

Antenna Pointing Mechanisms

A common movable element on spacecraft is the communication (or radar/microwave) antenna. Antenna Positioning Mechanisms (APMs) have long been used to perform the vital function of pointing the antenna bore sight to its target, and tracking to maintain the RF link to the spacecraft. APMs are typically two-axis gimbals. Antenna motion relative to the spacecraft is produced in either an elevation-over-azimuth or a cross-axis format. The elation-over-azimuth format can yield full hemispherical coverage, while the cross-axis format is useful for producing defined angular motion in spacecraft coordinates. The wide variety of antenna positioner assembles are compact, two-axis gimbals which are ideal for supporting and positioning small- to medium- to large-sized spacecraft communications antennas. Gimbals can be configured with either azimuth-elevation or X-Y (crossed axis) geometry, and several approaches to electrical cable management are available. Electrical cables can be carried across the gimbal axes in flexing loops, in cable wrap drums, or both. If an RF feed to the antenna is required, RF rotary joints can be integrated with the gimbal. Options for APMs include:

  • Rotary or Linear Actuators
  • Stepper or Brushless DC Motors
  • Encoders, Potentiometers or Resolvers
  • RF & Cable Management
  • Launch Locks