GB1113647A - Scanning antenna - Google Patents

Abstract

1,113,647. Aerials; pulse radar. NORTH AMERICAN AVIATION Inc. 21 June, 1966 No. 27753/66. Beddings H4A and H4D. An aerial comprises a feedline waveguide 21 which is regularly folded to provide a plurality of parallel sections each provided with a linear array of radiating elements 10, 11, 12 &c. Power is supplied at one end 23 of the feedline waveguide 21, a terminating load 22 being connected at the other end, and as the frequency of the supply is varied dual-plane scanning is obtained, in planes which are respectively parallel and perpendicular to the arrays. The feedline waveguide may be a stripline waveguide or a hollow waveguide of rectangular cross-section and the radiating elements may be slots in a face thereof. The radiating sections of feedline waveguide and the sections connecting them may be co-planar (Fig. 3, not shown), or the latter may be looped beneath the former (Fig. 4, not shown). The spacing between the elements of each array may be made a whole number of waveguide half-wavelengths at the broadside frequency and the distance along the waveguide between corresponding elements of adjacent arrays may be made a larger whole number of those half-wavelengths. It is stated that adjacent arrays may be displaced axially, or may be arranged with different numbers of radiating elements, in order to suppress side lobes, effect beam shaping &c., and that the aerial is suitable for airborne applications. A mono-pulse system may comprise two or four of the aerials (Fig. 5, not shown). The aerials are connected to magic-T's (26), (27), which are in turn connected to other magic-T's (28), (29). Power from a variablefrequency transmitter is applied to a sum terminal of the magic-T (28), so that the aerials are fed in phase. Received signals are obtained at the difference terminals of the magic-T's (28), (29), and are indicative respectively of the azimuth and elevation of a target.