GB704015A - Improvements in or relating to aerial systems - Google Patents

Abstract

704,015. Directive radio systems; radar. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. April 21, 1952 [June 27, 1951], No. 15276/51. Classes 40 (5) and 40 (7). An aerial system having transmission means and a spaced plurality of receiving means includes a lens directing plane polarized transmitted signals and a circular polarizer following the lens, and a receiver lens to direct waves which have passed through the circular polarizer and are plane polarized in a direction at right angles to the transmitted signal to the different receiving means, at least a part of the transmitter lens occupying the same part of the aerial aperture area as at least part of the receiver lens. Preferably the whole of the aperture area is used for both transmission and reception. 'The invention is particularly useful in radar systems in which the elevation and/or azimuth direction of a target is determined by comparing the received echo signals picked up at points a small distance apart. The two lenses may be one behind the other each consisting of a set of plates at right angles to the set constituting the other lens and the circular polarizer may consist of plates of the correct depth set at 45 degrees to the lens plates. In an embodiment having two receiving horns RH1 and RH2 and a central transmitting horn TH the plane polarized waves from horn TH are directed by a lens of vertical plates VLP occupying the whole aperture and then pass through the circular polarizer CP. Received signals circularly polarized in the opposite sense to those transmitted pass through the circular polarizer CP to a receiving lens of horizontal plates HLP in front of the plates VLP. The plates HLP are effectively two lenses one filling the upper half of the aperture 'and directing the received signals passing through it to receiver horn RH1 and the other filling the lower part of the aperture and directing signals passing through it to receiver horn RH2. A tapering funnel structure with two parallel sides and two diverging sides is provided extending from the horns to the lenses and a middle plate MP dividing the beams directed to horns RH1 and RH2 may extend from the lenses part of the way towards horn TH. A similar system having four receiving horns arranged at the corners of a square is described with reference to Figs. 6, and 8 (not shown).