Skynet 4 defence communication satellite project

The paper provides a brief history of United Kingdom defence satellite communications and sets out the general reasons why the new Skynet 4 satellite project has been initiated. The constraints on system design are explained and the outline requirements for the communications payload established. This provides two UHF repeater channels connected to an earth-cover antenna, four SHF channels connected to a variety of antennas which vary in beamwidth from earth-cover down to three degrees, and an EHF facility sponsored by the Royal Signals and Radar Establishment for advanced R and D purposes. Following the payload description, the remainder of the paper covers the overall design of the spacecraft and the various support subsystems necessary to achieve a successful mission.