Device for preventing a main beam parallax in a circularly polarized antenna camprising a curved reflector and an off-set primary radiating element

摘要

In the feed waveguide (7) to the antenna-horn emitter (8) waves of a higher mode than the fundamental are coupled in by means of a mode coupler (6) having an external signal input (5). The said waves have the same amplitude, but are in anti-phase to waves of that mode which would result in the same interfering main beam deflection as is actually caused by the curved reflector. A correction signal is applied to the external signal input of the mode coupler, this correction signal being derived from the fundamental signal in the feed waveguide by means of a coupler (3) and being adjusted to match, in terms of its phase and amplitude, by means of a correction network (4) in a correction signal path, so that broadband excitation of the anti-phase compensation wave is possible. The device according to the invention is suitable for application to satellite and directional radio antennas. IMAGE