Antennes embarquées à réflecteurs multisources

Three telecommunication satellite antennas, developed under the research and development programme of the European Space Agency, ESA, are described. The first one, operating around 1.6 GHz, is to equip advanced mobile communications satellites. It includes an 8 m unfurlable reflector and a system of multiple feeds. The influence of facets in the mesh reflector surface on the radiation patterns is discussed. The second one, for European coverage in the 10.7 to 11.7 GHz band, includes a 1.1 m offset reflector fed by 23 horns backed by a numerically machined waveguide distribution network. Performances of the antenna, with emphasis on the distribution network, are discussed. The third antenna, operating at 19 GHz, generates 0.25° low sidelobe spot beams to cover major European traffic centers. Its 4 m offset Cassegrain reflector is fed by a system of about a hundred horns. Each beam originates from a cluster of seven horns, some clusters, corresponding to closely adjacent beams, partially overlap. The design and performances of the antenna and its components are discussed in the paper.