Satellite communications system having frequency addressable high gain downlink beams
First Claim
1. A satellite communications system for communicatively interconnecting a plurality of terminal sites distributed over an area of the earth, comprising:
- an earth orbiting satellite; and
frequency responsive means carried by said satellite for forming a plurality of beams of electromagnetic radiation between said area on the earth and said satellite with each beam of radiation having a carrier frequency, said beam forming means including an array of radiating elements and an antenna for producing all of said beams, said beams being arranged in at least two groups thereof respectively covering two essentially contiguous zones within said area, the beams in said groups thereof intersecting said area on the earth in seriatim along an arc with the position of each of said beams along said arc being determined by the carrier frequency of the beam, said groups of beams being arranged essentially end-to-end along said arc, the beams in each group thereof being carried by the same preselected set of frequencies such said set of frequencies is reused by said beams.
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Accused Products
Abstract
A satellite communications employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.
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Citations
20 Claims
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1. A satellite communications system for communicatively interconnecting a plurality of terminal sites distributed over an area of the earth, comprising:
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an earth orbiting satellite; and frequency responsive means carried by said satellite for forming a plurality of beams of electromagnetic radiation between said area on the earth and said satellite with each beam of radiation having a carrier frequency, said beam forming means including an array of radiating elements and an antenna for producing all of said beams, said beams being arranged in at least two groups thereof respectively covering two essentially contiguous zones within said area, the beams in said groups thereof intersecting said area on the earth in seriatim along an arc with the position of each of said beams along said arc being determined by the carrier frequency of the beam, said groups of beams being arranged essentially end-to-end along said arc, the beams in each group thereof being carried by the same preselected set of frequencies such said set of frequencies is reused by said beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of communicatively interconnecting a plurality of terminal sites in an area on the earth using an earth orbiting communications satellite, comprising the steps of:
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(A) forming a first plurality of beams of electromagnetic radiation in an arc between said satellite and the earth and covering a first zone of said area and arranged in seriatim, said beams in said first plurality thereof respectively having carrier frequencies defining a preselected set; and
,(B) forming a second plurality of beams of electromagnetic radiation in said arc between said satellite and the earth and covering a second zone of said area essentially contiguous to said first zone and arranged in seriatim, said first and second pluralities of beams being arranged essentially end-to-end along said arc, said beams in said second plurality thereof respectively having the same carrier frequencies as said first plurality of said beams, such that said preselected set of frequencies is reused, each of said beams in said first and second pluralities thereof being formed such that the position of the beam along said arc is determined by the carrier frequency of the beam. - View Dependent Claims (18, 19, 20)
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Specification