Patent GB-549085-A (GB)
Title: Ultra-short wave antenna system
IPC: H01Q21/26
Filed: 1941-05-02
Abstract: 549,085. Wireless signalling. STANDARD TELEPHONES & CABLES, Ltd. May 2, 1941, No. 5725. Convention date, May 17, 1940. [Class 40 (v)] An antenna array comprises a plurality of radiators connected to a translating device by transmission lines differing in length by an integral multiple of a wave-length, the radiators .being connected to the transmission lines by branch lines having a length equal to an odd number of quarter wave-lengths, thereby producing currents equal in amplitude and phase, in all the radiators. The invention is described as applied to an antenna system comprising two or more " turnstile " units, each comprising a pair of doublets arranged in space quadrature in the same plane, the several units being in parallel planes and the corresponding doublets of the units being arranged: in two planes forming, say, the N-S and E-W panels. Fig. 1 shows on the left seven pairs of doublets 2, 3 spaced vertically a half-wave length apart and forming the N-S panel,' and on the right seven other pairs of doublets forming the E-W panel ; the Figure is purely diagrammatic and the doublets are arranged about a common axis as in Fig. 6. The transmission lines 14, 20 connecting the transmitter 10 to pairs 7 of the radiators in each panel differ in electrical length by an integral number of wave-lengths; and the radiators of each pair are connected at 22 to the transmission lines 20 by lines 21 of a quarter wave-length, so that all the corresponding radiators in each section of a panel are energized in phase,. the complementary radiators in the same panel being 180 degrees.out of phase. A phase-shitter 16 causes the doublets of the E-W panel to be 90 degrees out of phase with those of the N-S panel. so that the four. radiators, in each." turnstile " unit are energized in quadrature. Consequently, if the currents in the two sets of doublets are equal, there is.non-directional radiation in a horizontal plane, or it: the: currents are unequal directive effects are obtained. To remove sleet and static charges, the closed ends of the radiators of each doublet are connected by a high-resistance heater wire 9, so that current from a low-frequency source 17 can flow, when switch 19 is closed, in series over the transmission lines and each pair of doublets. All transmission lines are preferably of the co-axial type. One output terminal 22 of each section line 20 is connected to earth 25 by a cylindrical shield, 30, Fig. 4, represented by lead 24 in Fig. 1, and the branch lines 21 are enclosed by the shield 30 as shown in Fig. 4. The shield 30 may have a length, of one half-wave-length and serve as a support for a pair of doublets, the shields being, connected by sleeves to form a .supporting structure, Fig. 6 (not shown). Since the electrical distance from the terminals 22 of each section line 20 to the terminals 13 is an even multiple of a quarter-wave-length, the effective voltage at the various sets of terminals 22 in the sections of both panelsis equal to that of the voltage at terminals 13. Further, the currents in all the doublets in both panels are equal, even if they are of different impedance,: since they are connected to the section lines through quarter-wavelength lines. In a modified arrangement, Fig. 5 (not shown), instead of a. separate section line 20 for the various sections, 7, all the sections of the N-S panel are. connected to a single, panel line, and the sections of the. W-E panel are similarly connected..