Abstract: Electrically large, stepped-wall or smooth-wall, direct-radiating horn antenna apparatus that may preferably be used in satellite spot beam applications. Exemplary electrically large smooth-wall horn antenna apparatus comprises one or more input ports, an electrically large output port, and a smooth-wall or stepped-wall tapered section having a spline-shaped profile extending from the input port(s) to the output port of the apparatus. The spline-shaped profile is preferably monotonic and is preferably configured to generate a spot beam. The spline-shaped profile may be configured to support multiple frequency bands, and dual simultaneous polarization having either linear or circular polarization. The spline-shaped profile is defined by spline knots, and, the knot radii form a nondecreasing sequence. Preferably, the spline-shaped profile comprises a piecewise cubic Hermite interpolating polynomial spline that interpolates the shape of curves between the spline knots.

Abstract: Electrically large, stepped-wall or smooth-wall, direct-radiating horn antenna apparatus that may preferably be used in satellite spot beam applications. Exemplary electrically large smooth-wall horn antenna apparatus comprises one or more input ports, an electrically large output port, and a smooth-wall or stepped-wall tapered section having a spline-shaped profile extending from the input port(s) to the output port of the apparatus. The spline-shaped profile is preferably monotonic and is preferably configured to generate a spot beam. The spline-shaped profile may be configured to support multiple frequency bands, and dual simultaneous polarization having either linear or circular polarization. The spline-shaped profile is defined by spline knots, and, the knot radii form a nondecreasing sequence. Preferably, the spline-shaped profile comprises a piecewise cubic Hermite interpolating polynomial spline that interpolates the shape of curves between the spline knots.

Abstract: Feed horn apparatus for use in a multiple-feed antenna system. The present invention comprises a corrugated feed horn and an antenna array or cluster of feed horns arranged in a hexagonal lattice pattern. The feed horn comprises a hexagonal aperture formed by a circular-to-hexagonal transition section a corrugated section disposed adjacent to the circular-to-hexagonal transition section, a tapered section disposed adjacent to the corrugated section, and an input section having an input/output port disposed adjacent to the tapered section. The corrugated feed horn has good beam pattern symmetry, low cross-polarization, and sidelobe levels, along with an increased horn aperture area. As a result, the efficiency of the corrugated feed horn is improved by transitioning from a circular to the hexagonal aperture.