Patent GB-543299-A (GB)
Title: Multiple-unit steerable antenna systems
IPC: H01Q3/22
Filed: 1940-07-12
Abstract: 543,299. Directive wireless signalling. STANDARD TELEPHONES & CABLES, Ltd. July 12, 1940, No. 11631. Convention date, July 14, 1939. [Class 40 (v)] In a steerable antenna-array system of the type in which signals received by a series of aerials are fed to separate modulators whose outputs pass to the receiver through steering phasechangers, the total length of the path from wavefront to receiver, for an average or mean direction of space path, is made the same for each aerial, including the path in space before the aerial is reached, the high-frequency path between aerial and first modulator, the intermediatefrequency path between the latter and the phasechanger, and in some cases that between the phase-changer and the receiver. This is done in order that the settings of the steering phasechangers may be independent of frequency and that the components of a wide sideband may be uniformly well received. The paths from beat oscillator to modulator are made equal to those from aerial to modulator. In a system for steering in a vertical plane, Fig. 1, rhombic aerials A1 ... A7 feed a receiving station situated at the central aerial A4, steering phase-changers PC1 ... PC7 are lined up on the first phasechanger PC1 to which zero phase is assigned, and modulators D1 ... D7, fed by a beat oscillator BO, are connected to the phase-changers by lines IF1 ... IF7 whose lengths are such that the total distance from wave-front WF to aerial, from aerial along high-frequency line such as HF6 to modulator such as D6, and from modulator to phase-changer such as PC6, adds up for each aerial to (6D cos d + 3D) in the case in which there are seven aerials, where D is the distance between adjacent aerials and d is the angle of incidence ; and the lengths of the lines may be further modified to take account of the differences between the velocities in the lines and in space. This arrangement is intended to make the requisite setting of the phase-changers independent of changes in the signal frequency. It is adjusted for the mean angle d of arrival within the working range. The lengths of the lines HF connecting aerial to demodulator are different for different aerials, and in order that the ganging of the phase-changers may not thereby be invalidated upon change of signal frequency, the beat oscillator BO is connected to each modulator by a line whose length is equal to that of the line from aerial to modulator. This arrangement, or a simple modification of it, enables the intermediate frequency to be kept constant when the signal and beat-oscillator frequencies are changed. In another embodiment, Fig. 2 (not shown), the lines carrying the intermediate frequency lie partly between the modulators D1 ... D7 and phase-changers PC1 ... PC7, as shown in Fig. 1, and partly between the phase-changers and the intermediate-frequency amplifier IFA; and the phase-changers are lined up on the middle aerial A4, the phase of whose output is taken as zero, the remaining phasechangers being thus divided into two groups within which the controls are geared in the ratios 1:2:3 3 .. ; the controls are turned in directions which are opposite in the two groups.