WIDE BANDWIDTH HYBRID MODE FEEDS

摘要

The present invention relates to hybrid mode feeds which are capable of handling very wide bandwidths. In the present feed arrangements, a dominant TE11 mode is converted to the HE11 hybrid mode which is then launched. The TE11 to HE11 mode conversion is achieved by inserting a circular dielectric rod (12) into a flared end (11) of a smooth-walled cylindrical feedhorn until a small cylindrical section of the dielectric rod engages with the inner wall (15) of the unflared portion of the feedhorn. In one feed arrangement, the other end of the dielectric rod is similarly inserted into a flared end (21) of a corrugated cylindrical feedhorn section (22) until a short longitudinal section of the cylindrical portion of the rod is concentric with the corrugations of an unflared section of the feedhorn to provide a transition for the HE11 mode into the corrugated waveguide for subsequent launch. In a second feed arrangement, the dielectric rod at the aperture of the smooth-walled flared feedhorn is flared outward to end in a curved configuration which is shaped to minimize reflections back into the dielectric rod and provide a predetermined wavefront at the aperture of the feed.