GB1160696A - Directional Antenna Array having Improved Electronic Directional Control - Google Patents

Abstract

1,160,696. Aerials; pulse radar. COMPAGNIE FRANCAISE THOMSON HOUSTONHOTCHKISS BRANDT. 4 Oct., 1966 [14 Oct., 1965; 2 Nov., 1965], No. 44351/66. Headings H4A and H4D. [Also in Division H1] An aerial comprises spaced and selectivelyoperated primary radiators 1, 2, Fig. 1, and two spaced arrays 41 ... 4n, 51 . . . 5n of elements interconnected by phase shifters 61 ... 6n adjustable such that waves are focused and scanning is achieved by a phase-shifting programme which may be digital. The invention is applied to a pulse radar. If α denotes the angle subtended by F 1 , F 2 at the centre of array 4 and the lens is adjusted for transmission to a target in a direction S relative to the axis passing from F 1 through the centres of arrays 4, 5, then on reception re-adjustment is made tO correspond to an angle S + α. The corresponding phase shifts are made during an interval # overlapping the transmitted pulse and during the remainder of the pulse repetition period (p.r.p.) T, Fig. 3 (not shown). The phase shifters are also varied for each p.r.p. to achieve scanning. The phase shifter may be a continuous type by variation of current through ferrite but preferably it is a digital phase shifter utilizing a magic-T and diode switches in the two side arms (see Division H1 and Fig. 6 (not shown)). In general arrays 4, 5 are two-dimensional, Fig. 4 (not shown) with programmed digital control using binary numbers, the different orders of a number actuating digital phase shifters connected in series, Fig. 5 (not shown). The phase-shifter chain may include an additional unit introducing a phase shift f 1 (#) dependent only on wavelength (#) for correction of second-order effects. The radiation pattern may be controlled by a further phase shift f 2 (#). To afford a different radiation pattern during reception another phase shift f 3 (#) is added. The receiving element 2 may be of the multi-mode kind described in Specification 1,002,140 for a monopulse radar. A digital computer for controlling the phase shifters is described, Figs. 7, 8 (neither shown). Aerials 1, 2 may both be transmitting or both be receiving. In another embodiment a plurality of separate transmitters 91 ... 9N, Fig. 9, are connected to individual radiators 11 . . . 1N, with a single receiving aerial 2; radiators 11... 1N are preferably arranged in a part-circular or part-spherical array with their axes converging near the centre O of the lens array 4. A programmed controller 801 causes a keying cycle, Fig. 10 (where there are assumed to be six transmitters) and phase switching with the same target direction in one p.r.p. and switched target directions in successive p.r.p.s. This is achieved by an appropriate computer, Figs. 12, 13 (neither shown). The invention may be applied to a mirror 3, Fig. 14, using arrays 41 . . . 4n and 51 ... 5n; a Cassegrainian arrangement is mentioned.