Patent GB-624876-A (GB)
Title: Improvements in aerial systems
IPC: H01Q3/26
Filed: 1946-09-27
Abstract: 624,876. Directive radio systems. WESTERN ELECTRIC CO., Inc. Sept. 27, 1946, No. 28972. Convention date, Dec. 15, 1944. [Class 40 (vii)] An aerial system comprises a main array having a directive radiation pattern with a major lobe and one or more minor lobes and an auxiliary array having a radiation pattern with a primary lobe and one or more secondary lobes, wherein the auxiliary array is so disposed relative to the main array that a portion of said primary lobe coincides in space with one or more of said minor lobes and the phase and amplitude of said primary lobe is such, in relation to the minor lobe or lobes, that a substantial reduction in the amplitude of said minor lobe or lobes is obtained. The primary lobe may be aligned with the minor lobe or one of the minor lobes or it may be aligned with and in the same phase as the major lobe and of such angular width as to coincide with the major lobes, and the first minor lobes on each side thereof. Figs. 1 and 2 shows a system wherein the major lobe may be deflected to up-down, left-right, positions, the primary lobe being aligned with the undeflected position of major lobe and substantial reduction of the first minor lobes is achieved in each deflected position. The main array 1 comprises two parallel horizontal arrays of collinear dipoles with a cylindrical parabolic reflector 2 and 3 for each, the combined aperture is substantially square. The auxiliary array 9 comprises a further cylindrical reflector 10 and dipoles on the focal line thereof aligned with the main array. The square aperture of reflectors 2 and 3 may have sides six wavelengths long and the aperture 13 of the auxiliary array may also be square and have sides two wavelengths long. Fig. 1 shows that the main and auxiliary arrays are an integral unit which may be supported in a yoke assembly enabling them to be rotated. in azimuth and tilted as required. Fig. 2 shows the arrangement for connecting the sixteen dipoles 24 of the main array in phase by coaxial lines to translating device 28 through attenuator 37 and how the two dipoles 24 of the subsidiary array are also fed from device 28 through phase-shifter 49 and a further attenuator. The main array is divided into four parts, the left and right upper, and left and right lower, portions and sub-connectors 27 for each of these each have short-circuited quarter-wave coaxial lines 38 connected thereto. The switching device 39 driven by motor 45 has four stator plates 41 connected over switches 44 and lines 43 to approximately the mid-points of lines 38 and a rotor 42 capacitatively associated with the stator plates in pairs. This rotor retards the phase of the currents in successive halves of the main array to deflect the beam from the symmetrical position. Curves, Figs. 4 to 13 (not shown), are given showing the theoretical and measured reductions in amplitude in the first minor lobes for the particular embodiment described. It is stated that the auxiliary array may be used alone for searching to roughly locate an object's direction and the main array then switched in for accurate dual plane lobe switching. Specifications 588,159 and 600,611 are referred to.