Design of multiple feed per beam antenna based on a 3-d directional coupler topology

In this paper, an original Multiple-Feed per Beam (MFB) focal array architecture is designed. Significant overlapping of the feed clusters is achieved to enhance illumination performances within a size-constrained lattice. This focal array is set in front of a reflector to produce multiple beams with frequency and polarization re-use. The key component of the focal array is the beam-forming network, composed of polarizers, interleaved three-dimensional directional couplers, phase-shifters, and circular feed horns. Design considerations and final simulated radiation patterns are reported for a typical Ka-band multimedia mission.