GB550537A - Improvements in antenna systems - Google Patents

Abstract

550,537. Wireless signalling ; aerials. MARCONI'S. WIRELESS TELEGRAPH CO., Ltd. July 10, 1941, No. 8755. Convention date, July 10, 1940. [Class 40 (v)] An antenna comprises a rod-like radiator 11 having a. disc 19 mounted at the energized end to increase its capacity. The radiator 11 may have a tapered portion 16 arranged within a tapered sheath 15, the numbers 15, 16 being connected to a concentric transmission line 13, 14. The ratio of the diameter of conductor 16 to the bore of the sheath 15 is constant, so as to prevent reflection effects. The tapered sheath 15 is surrounded by a cylindrical shell 17 connected to 15 at its outer end. A conductor 23 connects the edge of the disc 19 to the supporting structure 20, thereby earthing the radiators against lightning &c. The disc 19 and the radiator 11 are each adjustable, Two or more of such radiators may be disposed at equal angles in a common plane and energized in such a way as to produce a rotating field, and-additional similar radiators may be arranged in parallel planes half a wave-length apart, Fig. 8 (not shown). The aerials may be energized simultaneously with two different wavelengths, e.g. by audio and video signals in television, the phase rotations of the two signals being in opposite directions. Fig. 9 shows an arrangement of this kind, the antenna 100 comprising four quarter-wave radiators in each of two planes energized with suitable phase displacement over four transmission lines 68 ... 71. The audio-transmitter A supplies energy to a pair of transmission lines 25, 25<1> and 26, 26<1> differing in length by half a wavelength, the load ends of the lines being turned to face each other, cross-connected as shown and surrounded by a shell 27, half a wavelength long and connected at its ends to lines 25, 26. A pair of balanced output lines 45, 46 and 55, 56 is connected to adjacent ends of the sheaths 25, 26, so that energy from transmitter A is supplied in push-pull relationship to the output lines. The video-transmitter B energizes a single transmission line 35, 36 connected through quarter-wave lines 28, 28<1> to the shell 27 and lines 25, 26, so that energy from B is supplied in push-push to the lines 45, 55. A loop 47 in one of the output lines ensures that energy in phase quadrature is obtained at their far ends, the phase rotation being in opposite directions for the two transmitters. Specification 528,817 is referred to.