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. Service may be optimized for (1) a particular geographical area
by using receiving sensors located in that area, monitoring the
polarization of the broadcast signal; or (2) a particular location with
the satellite operating in a unicasting mode (delivery of Internet data or
"local" video/audio broadcasts). A spread-spectrum waveform can also be
used on the downlink, with the resultant processing gain applying directly
to antenna area reduction and improved interference. Redundancy or
increased capacity can be achieved by locating a second satellite in the
same orbital location broadcasting the orthogonal circular polarization.
