BEAM WIDTH VARIABLE ANTENNA

摘要

PURPOSE:To reduce the effect due to the generation of a duct type phasing by detecting the reception level less than a prescribed value after a fixed period of time to control a drive part for secondary reflector with the detection output and therefore giving a parallel shift to the secondary reflector. CONSTITUTION:The present reception level which is less than a prescribed value is detected from the S/N of a pilot signal as well as the noise component. Then a reception level detector R/N detects that said reception level lasts longer than the time T. An output corresponding to the difference of reception levels is sent to a motor 5 to push out a secondary reflector 4 toward a main reflector surface 1. In this case, three secondary reflector posts 41 provided on the reflector 4 guide the hollow part of a post 33. As a result, the reflector 4 can have a smooth parallel shift toward the surface of the main reflector.