Steered-beam satellite communication system

DETAILED DESCRIPTION The present invention provides a system for communicating via satellite between ground stations.
The system comprises a set of ground stations spaced apart along an arc of the earth's surface and a satellite positioned above the earth in view of the arc.
An array of radiating elements is deployed on the satellite, and a frequency responsive beam former connected to the radiating elements is provided for forming a beam of electromagnetic radiation.
The beam is steerable in response to a carrier frequency of the radiation to intercept individual ones of the stations in seriatim.
The frequencies of an up-link carrier and of a down-link carrier respectively associated with respective ones of the ground stations vary monotonically with position along the arc to permit automatic positioning of a beam from the satellite to a ground station upon energization of a carrier frequency assigned to the ground station.
Another important feature of the invention permits the simplification of the structure of a communication satellite with respect to the construction of an antenna assembly.
A simplified antenna structure is obtained by the use of two confocal parabolic reflectors, one of which is large and one of which is small.
The large reflector is folded during launch of the satellite, and is subsequently unfurled for deployment.
The antenna configuration provides for a magnification of an antenna aperture of an array of antenna radiators so as to present a relatively large aperture for relatively few radiators.
These and other features and advantages of the present invention will be understood from the following more detailed description in accordance with the drawings in which: