Abstract: A coaxial turnstile junction (10) for combining and directing both satellite uplink and downlink signals. The junction (10) includes a tapered section (30) to provide better impedance matching of the downlink signal between a waveguide structure (14) and a plurality of symmetrically disposed downlink waveguides (38-44). The junction (10) includes a first end (26) that is in signal communication with an antenna feed horn (12). The junction (10) includes a cylindrical outer wall (28) and a cylindrical inner wall (18) that are coaxial and define an outer chamber (22) and an inner chamber (24). The outer wall (28) extends into the tapered section (30) where the tapered section (30) contacts the inner wall (18) and closes the outer chamber (22). The waveguides (38-44) are positioned around the outer wall (16) and are in signal communication with the outer chamber (22) through openings in the tapered section (30).

Abstract: An orthomode coupler (10) for directing both satellite uplink and downlink signals. The coupler (10) includes a waveguide structure (14) having a first cylindrical section (28), a conical section (30) and a second cylindrical section (34) providing a waveguide chamber (22) therein. The conical section (30) provides impedance matching of the downlink signal between the waveguide structure (14) and a plurality of symmetrically disposed downlink waveguides (38-44). The waveguides (38-44) are positioned around the waveguide structure (14) and are in signal communication with the waveguide chamber (22) through openings in the tapered section (30). Irises (46-52) are provided at the connection between the downlink waveguides (38-44) and the waveguide chamber (22) for impedance matching purposes.

Abstract: A satellite antenna system employing a dual-band feed horn and dual-band beam forming network. The feed horn provides a common aperture for both satellite uplink and downlink communications signal. The feed horn includes corrugations on an inside surface defining two sets of alternating channels having different depths to create circularly symmetric beams for the uplink and downlink signals. The antenna system includes at least one reflector, where the reflector shape, position, and the configuration of the feed horn, is determined so that the mainlobe of the lower frequency downlink feed signal illuminates the entire reflector, and the mainlobe of the higher frequency uplink feed signal illuminates an inner portion of the reflector. The first sidelobes of the higher frequency feed signal illuminate the outer portion of the reflector so that the uplink and downlink antenna signals have the same beamwidth, and thus cover the same cell size on the Earth.

Abstract: An orthomode coupler (10) for directing both satellite uplink and downlink signals. The coupler (10) includes a waveguide structure (14) having a first cylindrical section (28), a conical section (30) and a second cylindrical section (34) providing a waveguide chamber (22) therein. The conical section (30) provides impedance matching of the downlink signal between the waveguide structure (14) and a plurality of symmetrically disposed downlink waveguides (38-44). The waveguides (38-44) are positioned around the waveguide structure (14) and are in signal communication with the waveguide chamber (22) through openings in the tapered section (30). Irises (46-52) are provided at the connection between the downlink waveguides (38-44) and the waveguide chamber (22) for impedance matching purposes.

Abstract: A first embodiment of a waveguide coupler (10) has a substantially square cross-section with a width tapering from a first width a at a first end (12) to a smaller width b at a second end (14). Each side of the square waveguide coupler is provided with a turnstile port (16). The first end is coupled to a first waveguide (18) 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.