Shaped corrugated horns for cosmic microwave background anisotropy measurements

Novel corrugated horn have been modelled, manufactured and measured which g ive low-sidelobe patterns required by CMB Anisotropy experiments. These hor ns have a Back-to-Back structure with mode filtering at their centres. They are corrugated to give axial symmetric low-sidelobe patterns, profiled to reduce their length, and have: a Gaussian flare at their entrance apertures to further suppress sidelobes to -40dB. Modelling and experimental results show excellent agreement to well below 50 dB