Abstract: A spot beam satellite communications system and method for delivering information to user terminals at a high data rate. In a hub, a high data rate serial data stream is separated into parallel data streams that are modulated onto respective uplink transponders. The uplink transponders are transmitted by the hub to an earth-orbiting satellite, which translates the uplink signals to downlink frequencies. The satellite broadcasts the transponders to user terminals located in the desired beam coverage areas on the earth. The user terminal separates the downlink transponders and demodulates each of the downlink transponder signals to regenerate the parallel data streams. The parallel data streams are combined to reproduce the original serial data stream. By dedicating multiple transponders to a particular data stream, data can be relayed at a very high data rate by a communications satellite that employs a standard transponder frequency assignment scheme.

Abstract: A satellite communications system having ground user terminals, hubs, and a geosynchronous satellite. The satellite generates a network of spot beam coverage areas on the earth. A hub and at least one ground terminal are located in each of at least two spot beams. A first user terminal transmits an uplink signal according to a first signal protocol to the hub through the satellite. A second user terminal receives a downlink signal according to a second signal protocol through the downlink spot beam from the hub through the satellite. The hub may be located in the same spot beam coverage area as the first or the second user terminal or may be located in an altogether different spot beam coverage area.

Abstract: A satellite communications system having ground user terminals, hubs, and a geosynchronous satellite. The satellite generates a network of spot beam coverage areas on the earth. A hub and at least one ground terminal are located in each of at least two spot beams. A first user terminal transmits an uplink signal according to a first signal protocol to the hub through the satellite. A second user terminal receives a downlink signal according to a second signal protocol through the downlink spot beam from the hub through the satellite. The hub may be located in the same spot beam coverage area as the first or the second user terminal or may be located in an altogether different spot beam coverage area.

Abstract: A satellite-based communications system operating at high data rates in a broadcasting (multicasting) mode enables the use of mobile ground terminals with low profile antennas whose areas are significantly smaller than previous embodiments not using this invention. The invention can be applied to existing (in-orbit) or new satellites (including those in non-geostationary orbits) operating with linearly polarized downlink transponders. Important embodiments include the use of Ku FSS satellites providing service within the continental U.S. (“CONUS”), and the use of Ku BSS satellites operating within Europe. Transponder pairs on board the satellite with opposite linear polarization, but overlapping frequency bands, receive a specially processed uplink waveform from an uplink facility.

Abstract: A satellite-based communications system operating at high data rates in a broadcasting (multicasting) mode enables the use of mobile ground terminals with low profile antennas whose areas are significantly smaller than previous embodiments not using this invention. The invention can be applied to existing (in-orbit) or new satellites (including those in non-geostationary orbits) operating with linearly polarized downlink transponders. Important embodiments include the use of Ku FSS satellites providing service within the continental U.S. (“CONUS”), and the use of Ku BSS satellites operating within Europe. Transponder pairs on board the satellite with opposite linear polarization, but overlapping frequency bands, receive a specially processed uplink waveform from an uplink facility.

Abstract: A geodesic slotted cylindrical (GSC) antenna having a shaped elevation pattern and a narrow or shaped azimuth beam that can be scanned 360.degree. in the azimuth plane. The azimuth radiation pattern of the GSC antenna can be reconfigured through the use of interchangeable beam forming feed networks. The GSC antenna comprises a parallel plate waveguide formed by spaced-apart inner and outer cylinders constructed from conductive material. Radiation occurs from a stack of circumferential slots in the outer cylinder. By varying the slot spacing with the azimuth angle, the elevation pattern can be altered as a function of the azimuth angle. The GSC antenna can be excited by a number of equally spaced probes on a circle at the base of the cylinders. The feed radius is typically smaller than the outer cylinder's radius to minimize the number of active components and to minimize the number of spurious ray paths that can wrap around inside the cylinder's parallel plate region.

Abstract: A 90.degree. coupling circuit cascaded with a pair of hybrid mode latchable phase shifters provides polarization agility for an RF radiator module of the type typically used in a phased array. For example, such radiator modules typically may utilize an active microwave integrated circuit (MIC), a monolithic microwave integrated circuit (MMIC) or a passive reciprocal hybrid mode element (RHYME) circuit. These circuits are arranged to provide duplex RF transmit/receive functions with controllable phase shifts at each radiator site in a phased array. By appropriately setting the two controllable phase shifters to different combinations of phase shifts (e.g., 0.degree. and/or 90.degree.) to a dual orthogonal mode radiator, different spatial polarizations for RF radiator transmit/receive functions can be defined. The radiator itself may include a square or circular waveguide including, in some cases, a reciprocal dielectric quarter-wave plate and a non-reciprocal ferrite quarter-wave plate.

Abstract: A miniaturized waveguide mode ferrite RF phase shifter is efficiently transitioned to a matched impedance microstrip transmission line mode at either end to result in an ultra small, efficient and lightweight essentially "planar" phase shifter device having a single ferrimagnetic toroid.

Abstract: The present invention is for an apparatus and method of fast-switching a dual-toroid microwave ferrite phase shifter. A first circuit is provided for controllably switching the ferrite in one of the toroids between a saturated and partially saturated states. A second conduit is provided for controllably switching the ferrite in the other of the toroids between a saturated and partially saturated states. A control circuit is provided for controlling the first and second circuits such that the ferrite in at least one of the toroids is maintained in the saturated state at any given time such that any desired phase shift may be achieved with only one switching operation for each toroid. The present invention provides new reference states such that there are two reciprocal phase states for any given phase state such that a reciprocal phase state may always be achieved with only one switching operation for each toroid.