Effective 8mm-Band (30–38 GHz) compact feed for multi-beam radio telescope: Simulation and measurement results

A compact smooth-walled spline-profile horn covering the 30-38 GHz frequency band (8 mm radioastronomy band) to be used in a multibeam receiving array of a radio telescope has been optimized, manufactured and tested. The radiation pattern of this horn has sidelobe levels less than -24 dB in both principal planes across the band, cross-polarization levels better than -20 dB, input return losses better than 20 dB and the 3 dB-beamwidth is of the order of 40deg over the frequency band. Mutual-coupling of adjacent horns is less than -38 dB. We consider such a horn as one of the best candidates for an array feed for a multi-beam radio telescope.