Feedhörner

Feedhörner, or feed horns, are a type of antenna element that serves as the interface between a guided wave in a transmission line or waveguide and radiated electromagnetic energy in free space. They are used to launch or collect signals for reflector antennas such as parabolic dishes, as well as in radar and radio astronomy systems. The horn’s shape and dimensions determine the amplitude and phase distribution across the aperture, affecting beam pattern, phase center, polarization, and bandwidth. Common geometries include conical and pyramidal horns; corrugated horns use concentric grooves on the inner wall to improve polarization purity and impedance matching over wide bandwidths.

Construction typically involves precision machined metal components, often aluminum or brass, sometimes copper, with tight tolerances. Manufacturing methods include milling, extrusion, electroforming, or additive manufacturing for prototyping. The horn is usually integrated with a waveguide-to-horn transition and, for dual-polarization systems, with orthomode transducers (OMTs) or polarizers.

Applications are widespread in satellite communications, terrestrial and spaceborne radar, and radio astronomy. In astronomy, feed horns illuminate the telescope’s reflector and feed the receivers; in communications, they provide high-gain, directive radiation with controlled sidelobes. Performance is characterized by aperture efficiency, return loss, cross-polarization discrimination, and bandwidth, with design trade-offs between size, weight, and operating frequency.