Communications Satellites Using Arrays

Passive reflectors require large ground antennas and powers but permit use of unstabilized reflectors. Active systems, on the other hand, offer attractive performance through high directivity antennas but generally require stabilized vehicles. Further, the reliability of a satellite repeater amplifier is a critical factor. Automatic angle return arrays are investigated for both passive and active systems. These arrays, called Van Atta arrays, return a signal in the direction of incidence and are effective over at least ±45°. Thus only partial stabilization or single axis (spin) stabilization need be used, greatly simplifying the station-keeping orbit control problem. An active Van Atta (AVA) scheme has inherently high reliability since many of the distributed amplifiers can fail without serious performance degradation. The distributed structure also allows use of low-power solid-state amplifiers. This paper points up the salient advantages of the AVA system, and de´ineates the major areas where further work is indicated.