Patent ID: 6931245
Filing Date: 2005-08-16
Classification: H04H

Abstract:
1. An apparatus for downconversion of linearly and circularly polarized signals, wherein the linearly polarized signals have a different frequency than the circularly polarized signals, said apparatus for use in conjunction with an antenna or waveguide, said antenna or waveguide operative to receive vertically and horizontally polarized components of said linearly and circularly polarized signals, said apparatus comprising: (a) a first LNB input and a second LNB input, said first LNB input operative to receive the vertically polarized components of the linearly and circularly polarized signals and said second LNB input operative to receive the horizontally polarized components of the linearly and circularly polarized signals; (b) a first amplifier and a second amplifier coupled to said first LNB input and said second LNB input, respectively, said first amplifier operative to receive and amplify a signal from said first LNB input and said second amplifier operative to receive and amplify a signal from said second LNB input; (c) a first diplexer coupled to said first amplifier, said first diplexer comprising a low pass filter and a high pass filter, said first diplexer operative to receive said signal from said first amplifier and to separate said signal from said first amplifier into a first frequency band and a second frequency band, said first frequency band corresponding to said linearly polarized signal and said second frequency band corresponding to said circularly polarized signal, said first diplexer additionally having a first output and a second output, said first output for outputting said first frequency band and said second output for outputting said second frequency band; (d) a second diplexer coupled to said second amplifier, said second diplexer comprising a low pass filter and a high pass filter, said second diplexer operative to receive said signal from said second amplifier and to separate said signal from said second amplifier into a first frequency band and a second frequency band, said first frequency band corresponding to said linearly polarized signal and said second frequency band corresponding to said circularly polarized signal, said second diplexer additionally having a first output and a second output, said first output for outputting said first frequency band and said second output for outputting said second frequency band; (e) a pair of linear mixers, each one of said pair of linear mixers coupled to a first local oscillator, a first mixer of said pair of linear mixers having an input coupled to said first output of said first diplexer, and a second mixer of said pair of linear mixers having an input coupled to said first output of said second diplexer, said pair of linear mixers operative to downconvert said first frequency bands from said first outputs of said first and second diplexers; (f) a 90 degree combiner having a first input and a second input, said first and second inputs coupled to said second outputs of said first and second diplexers, respectively, said 90 degree combiner operative to introduce phase shifts into the signals entering said first and second inputs so as to separate left-hand and right-hand circularly polarized signals of said circularly polarized signals, said 90 degree combiner having a first output and a second output, said first output for outputting said left-hand circularly polarized signal and said second output for outputting said right-hand circularly polarized signal; and (g) a pair of circular mixers, each one of said pair of circular mixers coupled to a second local oscillator, a first mixer of said pair of circular mixers having an input coupled to said first output of said 90 degree combiner, and a second mixer of said pair of circular mixers having an input coupled to said second output of said 90 degree combiner, said pair of circular mixers operative to downconvert said left-hand and right-hand circularly polarized signals.