Near field Cassegrain antenna - has collecting reflector with circular segment steps movable by flap device to produce 180 degree phase shift

摘要

The antenna consists of a primary radiator (1) (eg a horn), an auxiliary reflector (2), a collecting reflector (3) and a main reflector (4). The auxiliary reflector is located behind a central hole (5) in the main reflector. The collecting reflector has quarter-wave steps to introduce a phase shift of 180 degrees. The steps are formed by segments (12) of a circle centered on the collecting reflector and moved by a flap device (13-16). When in operation, the stops lie on the collecting reflector, and when not in operation they lie outside the paths of the radiation between radiator and collecting reflector and between collecting reflector and main reflector.