Sub-reflector for directional horn aerial - carries two spaced auxiliary elements, one conical and one frusto=conical, both having different slopes

摘要

The directional aerial using the Cassegrain principle has a sub-reflector (1) with two auxiliary elements (2,3) mounted on its outside surface. The outer element (2) which is much smaller than the other (3) is conical, while the larger element is frusto conical, and both form a conical point on the outside surface. The two elements are mounted on concentric threaded spindles (4,5), each with a control disc (6,7) attached so that they can be axially adjusted. The two elements are spaced apart by a gap which is less than the wavelength of the operating frequency. The largest diameter of the elements is between 1/7 and 1/10 of the diameter of the sub-reflector. The ratio of the diameters of the two elements is between 1:3 and 1:4. The two elements have different angles of slope.