Abstract:
The Spacecraft Antennas & Beam Steering Methods for Satellite Communication System comprises an advanced active element phased antenna array (10). The present invention utilizes electronic beam steering to provide extremely high gain signals. In one of the preferred embodiments of the invention, a satellite (S) includes an Earth-facing array (10) of hexagonal antenna facets (12) that are mated together along their six-sided boundaries to form a slightly flattened, hemispherical shell. The antenna array (10) is connected to two rectilinear, unfurled, solar panels (14) which trail the body of the spacecraft (S) and provide electrical power. The antenna array (10) is designed to transmit and receive signals from terrestrial units that are located within the footprints (20) produced by the electronically steered beams (19).
Abstract:
The Switching Methods for a Satellite Communication System overcome the limitations encountered by conventional packet switching using virtual circuits. The present invention utilizes a ''datagram'' approach that routes every packet (22) conveyed by the system independently at every node in the network. The packets (22) are directed along an optimized pathway through the network by a fast packet switch (38) that directs traffic based on instructions from an adaptive routing processor (14) that continuously runs an adaptive routing algorithm (16). This adaptive routing processor (14) works together with an input packet processor (28) and a routing cache memory (20) to monitor the rapidly changing topology of each satellite (S) in the constellation and the distribution of traffic among its nodes and links. The input packet processor (28) functions like a gatekeeper or guide that extracts the destination node address (32) from each packet (22) and uses it to access routing information stored in the routing cache memory (20).
Abstract:
Beam Compensation Methods pertain to the management of radio beams (11) which are generated by a constellation of satellites (S). These beams (11) are precisely controlled so that they illuminate ''Earth-fixed cells'' as opposed to ''satellite-fixed cells''. In previous satellite communication schemes, spacecraft which are not held stationary over one particular location on the Earth in geo-synchronous orbits fly over large regions of the Earth very rapidly. In a system that employs satellite-fixed cells, the ''footprint'' (10) of the radio beams (11) propagated by the spacecraft defines the zone on the ground called a ''cell'' which is illuminated by the spacecraft. This satellite-fixed cell moves constantly as the spacecraft moves around the globe. In sharp contrast, an ''Earth-fixed cell'' (14) is a stationary region mapped onto the surface of the Earth that has permanent fixed boundaries, just like a city or a state.
Abstract:
A superconducting millimeter wave array (10) is disclosed. In one of the preferred embodiments of the invention, the array (10) is enclosed in a cryogenic envelope (16) that has one side that is transparent to microwave radiation. A superconducting microstrip layer (24) formed on a saphire substrate (20) attached to the envelope (16) is coupled to transmit and receive circuitry via a signal waveguide (18). Each microstrip terminal (25) on the superconductor layer (24) is aligned with a slot (29) formed in a slotted ground plane (27) residing next to the superconductor layer (24). A heat reflective dielectric layer (26) is placed next to the superconducting layer (24), and is also adjacent to a layer of conductive radiating elements (30) and a layer of parasitic patches (35). Individual conductive radiating elements (31) and the parasitic patches (35) are also positioned in line with the microstrip terminals (25) and the slots (29) in the ground plane (22).
Abstract:
Terrestrial antennas (10A, 10B and 10C) which are capable of transmitting and receiving radio signals directly to and from satellites in low Earth orbit are disclosed. The preferred embodiments of the invention employ printed circuit antenna elements (18) measuring only a fraction of an inch (less than 2 cm) in diameter. One embodiment (10A) includes an elevation array residing on a circular surface (14) and an azimuth array residing on a conical surface (12). This first embodiment (10A) resembles a flattened pyramid. Both the top and the curved exterior of the pyramid support circular, slotted, printed circuit patches (18). Other embodiment of the invention employ hemispherical (10B) or cylindrical (10C) configurations.
Abstract:
The disclosed satellite communication system comprises a dynamic constellation (C) of satellites (S). The system includes a number of low-earth orbiting spacecraft (S) which travel in orbital planes. Each of the individual spacecraft (S) functions as an independent sovereign switch which knows the position of its neighbors, and independently handles traffic without ground control. The satellites (S) are capable of transporting calls directly to users of portable, mobile and fixed radio terminals; and via gateways to users of the public switched telephone network. The present invention offers direct communication between satellites (S) of the constellation (C) and individuals using lightweight, portable telephones. The direct link is made possible by miniature antennas (210) coupled to the handheld phones.
Abstract:
A series of spacecraft designs (10, 32 and 118) for a Satellite Communication System is disclosed. One of the preferred embodiments of the invention called "Domesat" (10) includes a hemispherical, high-gain, electronically-steered antenna array (12) that is always pointed toward the Earth (E). Hexagonal antenna panels (14) are held together by tubular and spherical connectors (28 and 30). The upper portion of the satellite (10) incorporates a space-facing array (18) of panels (20) which are always pointed toward the zenith (Z). The interior of the dome-shaped antenna array (12) is used to store solar cell panels (16) which unfurl through an opening (15) in the space-facing array (18) when the spacecraft (10) reaches its final orbit. Another embodiment of the invention called "Batsat" (118) comprises a central body (120) and two arms (122 and 124) that include disc-shaped antenna panels (131-139) and solar/thermal panels (140 and 141).