Trw Limited

Northrop Grumman Systems Corporation

Gregory P Junker

Vrage Minassian

Charles W Chandler

Ann L Peebles

A coaxial turnstile junction ( ) for combining and directing both satellite uplink and downlink signals. The junction ( ) includes a tapered section ( ) to provide better impedance matching of the downlink signal between a waveguide structure ( ) and a plurality of symmetrically disposed downlink waveguides ( ). The junction ( ) includes a first end ( ) that is in signal communication with an antenna feed horn ( ). The junction ( ) includes a cylindrical outer wall ( ) and a cylindrical inner wall ( ) that are coaxial and define an outer chamber ( ) and an inner chamber ( ). The outer wall ( ) extends into the tapered section ( ) where the tapered section ( ) contacts the inner wall ( ) and closes the outer chamber ( ). The waveguides ( ) are positioned around the outer wall ( ) and are in signal communication with the outer chamber ( ) through openings in the tapered section ( ). Irises ( ) are provided at the connection between the downlink waveguide ( ) and the outer chamber ( ) for impedance matching purposes. Satellite downlink signals from the downlink waveguides ( ) are sent to the feed horn ( ) through the outer chamber ( ). Satellite uplink signals received by the feed horn ( ) are directed through the inner chamber ( ) to receiver circuitry. The dimensions of the irises ( ) and the flare angle of the tapered section ( ) are selected and optimized so that the downlink signal propagating down the waveguides ( ) is impedance matched to the downlink signal propagating through the outer chamber ( ).

Wideband TE11 mode coaxial turnstile junction

A first embodiment of a waveguide coupler (,) has a substantially square cross-section with a width tapering from a first width a at a first end (,) to a smaller width b at a second end (,). Each side of the square waveguide coupler is provided with a turnstile port (,). The first end is coupled to a first waveguide (,) to couple the turnstile ports with the first waveguide, while the second end is coupled to a second waveguide, coupling the first and second waveguides together. Signals throughout the waveguide coupler's lower frequency band can be coupled between the turnstile ports and the first waveguide, while signals throughout the higher end of the frequency band can be coupled from the first waveguide to the second waveguide, and signals within the frequency band can be coupled from the second waveguide to the first waveguide. A second embodiment (,) includes a first waveguide coupling section (,) having a first end (,) with a substantially circular cross-section which is connected to a circular first waveguide (,), and a second end (,) with a substantially square cross-section. A second waveguide coupling section (,) has a configuration like waveguide coupler (,) of the first embodiment. The larger end of the second waveguide coupling section is coupled to the first waveguide coupling section to couple the turnstile ports with the first waveguide. The second of the second waveguide coupling section is coupled to a square second waveguide to couple the first and second waveguides together.

Waveguide coupler

An antenna system comprising a feed array, a subreflector and a main reflector which are oriented to define a offset gregorian antenna geometry. The feed array is comprised of a plurality of separate feeds which are aligned on a predetermined contour. Each feed array is coupled to a feed network which acts to combine the illumination beams of clusters of a preselected number of feeds to produce a plurality of composite illumination beams. Each composite illumination beam is directed to be incident upon a separate predetermined location on the subreflector which directs the composite illumination beams and directed towards the main reflector. Each composite illumination beam is reflected by the main reflector in a preselected direction so that each composite illumination beam forms an antenna beam that impinges a predetermined coverage area on the Earth. Each antenna beam defines a separate coverage cell in the coverage area, wherein the position and orientation of the feeds, the subreflector and the main reflector provides antenna beams over a full Earth field of view coverage area where each antenna beam is approximately symmetrically shaped.

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El Segundo, CA, United States of America

Gregory P Junker