GB938929A - Improvements in or relating to radio detection systems - Google Patents

Abstract

938,929. Radar. COMPAGNIE FRANCAISE THOMSON-HOUSTON. Jan. 13, 1960 [Jan. 13, 1959], No. 1259/60. Class 40 (7). A V-beam radio detection system utilizes an aerial arrangement radiating three or more flat beams inclined at a relatively small angle to each other (i.e. smaller than the usual 45 degrees angle in known two-beam systems). Fig. 1 shows one embodiment utilizing three beams A, B, C rotating about vertical axes, the plane of beam B being vertical with respect to the horizontal whilst that of beams A and C are slanting with respect to the horizontal. Each aerial is connected to a respective bearing angle computer 5, 6, 7 during fixed instants which include the passage of the particular beam over the target by means of a gate 8 controlled by a known automatic tracking device via input 9. The outputs of the bearing computers associated with adjacent beams are supplied to elevation angle computers 10, 11 and the mean of the outputs of the latter derived in an adder 12 to provide a signal which is utilized in a device 13 together with range information (input d) to compute the altitude of the target. Additionally, the output of computer 6 is representative of the bearing angle when the vertical beam B passes over it. In a modification of Fig. 1, the outputs of the elevation angle computers 10, 11 are utilized in separate devices, each equivalent to device 13, together with range information, to compute respective values of altitude, the mean of which is then derived (Fig. 2, not shown). In a second embodiment (Fig. 3), four beams D, E, F, G, are utilized the planes of all of which slant with respect to the horizontal, with those of beams E and F nearer to the vertical than the planes of D and G. As in the embodiment of Fig. 1, bearing angle computers 22 . . . 25 are connected in pairs associated with adjacent beams to elevation angle computers 29 . . . 31 the mean of the outputs of which is derived in an adder 32 and utilized in device 33 together with range information (input A) to compute the altitude of the target. Additionally, the bearing angle of the latter when it crosses the vertical plane of symmetry of the beams is derived in device 28 by adding the outputs of the bearing computers 23, 24. An advantage of the invention over known twobeam systems resides in the improved degree of precision with which the altitudes of fast moving targets may be computed. Specification 938,930 is referred to.