Near field cassegrain antenna - has lobe widened using extra reflector or dielectric lens in path of primary radiation

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. A dielectric lens (6) or an extra reflector (14)is used to widen the radiation lobe and is located behind the central hole (5) in the main reflector. The lens or extra reflector has its focus arranged such that solely a part of the collecting reflector, and therefore also a part of the main reflector, is irradiated. The advantage lies in avoiding using moving parts other than those needed to insert the lens or extra reflector into the radiation path.