SCANABLE ANTENNA ARRANGEMENTS CAPABLE OF PRODUCING A LARGE IMAGE OF A SMALL ARRAY WITH MINIMAL ABERRATIONS

摘要

SCANABLE ANTENNA ARRANGEMENTS CAPABLE OF PRODUCING A LARGE IMAGE OF A SMALL ARRAY WITH MINIMAL ABERRATIONS The present invention relates to antennas which have reflector arrangments that produce a large image with minimal aberrations at the exit aperture thereof of a small feed array. In the present arrangment, the feed array is placed at the conjugate plane relative to the exit aperture of a geometrically confocal reflector system comprising a parabolic main reflector and a parabolic subreflector so that exact imaging of the array is obtained at the exit aperture. In such arrangements, alignment and surface accuracy errors of the various reflectors can be easily corrected by appropriately changing the phase or the position of the associated elements of the feed array. A threereflector arrangement having sequential geometric confocality is disclosed which also alters the focal length of the main reflector sufficiently to permit the inclusion of polarization and/or frequency diplexing means in the overall reflector system.