Dual offset reflector multibeam antenna for international communications satellite applications

Dual offset reflector antenna systems offer exciting possibilities for achieving both low scan losses and low cross polarization in geosynchronous communications satellite antennas providing narrow ( ) and multiple beam frequency reuse coverages over an conical field of view. Novel geometrical configurations for the reflectors are characterized by simultaneously achieving: 1) blockage free apertures for all element beams within the conical field of view, 2) compatibility with large planar feed arrays, 3) additional degrees of design freedom by orientation and shaping of reflector surfaces for depolarization and scan loss optimization, and 4) large effective ratio achieved in compact and foldable geometries. A comparison of new front-fed offset Cassegrain (FFOC) and side-fed offset Cassegrain (SFOC) systems is made.