Antenna feed system for receiving circular polarization and transmitting linear polarization
First Claim
1. A system for coupling an antenna feed to means having one port for receiving circularly polarized signals and to means having one port for transmitting linearly polarized signals comprisingtwo transmission paths,means connected to said antenna feed for dividing a received circularly polarized signal into separate linearly and orthogonally polarized signals in said two transmission paths,a quadrature hybrid junction having two input ports, each connected to one of said two transmission paths, and one output port, and having its output port connected to said one port of said receiving means for combining said two linearly and orthogonally polarized signals into a circularly polarized signal, anddiplexing means for coupling said one port of said linearly polarized transmitting means into at least one of said two transmission paths for transmitting a linearly polarized signal through said antenna feed.
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Abstract
An object is to provide for receiving a circularly polarized signal from an antenna feed (10) connected to orthogonally spaced antenna elements (11, 12, 13, 14) and for transmitting a linearly polarized signal through the same feed without switches, and without suffering a 3 dB polarization mismatch loss, using an arrangement of hybrid junctions. The arrangement is comprised of two dividing hybrid junctions (15, 16), each connected to a different pair of antenna elements and a summing hybrid junction (17). In one embodiment, a receiver (18) is connected to the summing hybrid junction directly. A diplexer (19a or 19b) is used to connect a transmitter (20a or 20b) to only one pair of antenna elements. In an alternative embodiment, designated left and right circularly polarized (LCP and RCP) transmitters (21, 22) are connected to the summing hybrid junction by separate diplexers (23, 24), and separate LCP and RCP sensitive receivers (25, 26) are connected to the diplexers in order to transmit linearly polarized signals using all four antenna elements while receiving circularly polarized signals as before. An orthomode junction (30) and horn antenna (32) may replace the two dividing hybrid junctions (15, 16) and antenna feed (10).
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Citations
8 Claims
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1. A system for coupling an antenna feed to means having one port for receiving circularly polarized signals and to means having one port for transmitting linearly polarized signals comprising
two transmission paths, means connected to said antenna feed for dividing a received circularly polarized signal into separate linearly and orthogonally polarized signals in said two transmission paths, a quadrature hybrid junction having two input ports, each connected to one of said two transmission paths, and one output port, and having its output port connected to said one port of said receiving means for combining said two linearly and orthogonally polarized signals into a circularly polarized signal, and diplexing means for coupling said one port of said linearly polarized transmitting means into at least one of said two transmission paths for transmitting a linearly polarized signal through said antenna feed.
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6. In a two-way signal transmission system for receiving circularly polarized signals at a receiver 18 and transmitting linearly polarized signals from a transmitter, the combination comprising
an orthomode antenna means having two ports at which orthogonal linearly polarized signals are provided in response to circularly polarized signals received, a diplexer having three ports, one port coupled to said orthomode antenna means and one port coupled to said transmitter for coupling said transmitter to said orthomode antenna means for transmission of linearly polarized signals, and a third port, and a 90° - hybrid junction having a pair of input ports connected respectively to said ports of said antenna means, one of said pair of input ports of said hybrid junction being connected to receive a signal from the third port of said diplexer, said hybrid junction having an output port at which the sum of signals received at said pair of input ports is produced as a circularly polarized signal, said output port being connected to said receiver.
- View Dependent Claims (7, 8)
Specification