GB787756A - Improvements in or relating to wave guide mouth structures for projecting beams of electro-magnetic waves - Google Patents

Abstract

787,756. Aerials. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 6, 1956 [June 2, 1955], No. 15844/55. Class 40 (7). The invention relates to a waveguide fed antenna structure having similar E and H plane polar diagrams so that lens structures or paraboloidal reflectors can be efficiently illuminated by the antenna. In accordance with the invention, the broad sides of a rectangular waveguide 1 are extended beyond the mouth 3 of the guide by means of a pair of tapered extension plates 4. Each plate is of the same width as the guide at the end where it is attached thereto and tapers down to a relatively small width at the distant end. A conductive rod 5 joins the distant ends of the plates and lies in a plane perpendicularly bisecting the guide mouth and parallel to its narrow faces. Further, a pair of conductive radiating members 6 are positioned at the distant ends of the plates and extend outwardly. These members 6 may be extensions of the pin 5 which can extend through holes in the plates and be firmly connected thereto or they may be upstanding flanges at or near the narrow ends of the plate. The overall length of the two members 6 and the conductive member 5 is preferably half the operating wavelength and the angle a indicated on Fig. 3 is of the order of 60 degrees. If desired, upstanding flanges 7 may be provided at or near the waveguide mouth on the broad or all of the external faces of the guide 1.