GB1148888A - Improvements in or relating to directional aerials - Google Patents

Abstract

1,148,888. Aerials. MARCONI CO. Ltd. 26 July, 1966 [15 Oct., 1965], No. 43919/65. Heading H4A. In a directional aerial a plurality of pairs of convergent waveguides feed into a common radiating aperture, their other ends terminating in a further waveguide which is centrally fed, the arrangement being such that for each pair the lengths of their paths from the central feed to the said aperture are substantially the same. As described, a radiator fed from a central waveguide 11 is formed from side plates 1, 2 and a back plate comprising straight portions 3, 3 and angled outer portions 4, 5. The radiator is divided into cells forming a linear array by a series of sloping spacing plates 10, 8, 8... on one side of the centre and a series of oppositely sloping spacing plates 9, 7, 7 ... on the other side of the centre. The spacing plates stop short of the back plate, and the ends of the spacing plates 9, 10 are joined by a plate 6 which is parallel to the straight portions 3, 3. The top surface of the radiator may be made of two flat portions meeting at an obtuse angle at the centre in order to improve matching, and the ends of the spacing plates may be curved outwards for the same purpose (Fig. 4, not shown). The side plates 1, 2, may be extended beyond the ends of the spacing plates and may be bent to form a flared aperture. The central feed waveguide may be divided into two waveguides (11<SP>1</SP>), (11<SP>11</SP>), Fig. 3 (not shown), each supplying one side only of the aerial, and connected together by means of a 3dB directional coupler (12). This arrangement permits " static split " operation. The aerial is stated to be effective over a wide bandwidth, for example with a 3 : 2 ratio.