GB560271A - Antennas - Google Patents

Abstract

560,271. Wireless signalling. STANDARD TELEPHONES & CABLES, Ltd. Nov. 6, 1942, No. 15701. Convention date, Nov. 8, 1941. [Class 40 (v)] An antenna system for radiating or receiving with equal intensity in all directions in a given plane comprises a pair of elongated sheet conductors 90, 91 spirally disposed around a two-conductor transmission line, each sheet conductor being connected along one longitudinal edge to a different conductor of the line. The sheet conductors may be regarded as surfaces generated by rotating an elemental dipole antenna about the axis of the line, and simultaneously moving it along the axis to provide a plurality of like antenna sections in which the spacing in angular degrees between any two assumed positions of the elemental antenna is equal to the spacing in electrical degrees between the points of connection of the elemental antenna to the line conductors. The transmission line may comprise a vertical mast with inner and outer conductors 101, 102 or two vertical masts each forming one conductor, Fig. 4 (not shown). The structure is earthed at its base through a quarter-wave-length line section 17 to provide a low impedance for lightning and frequencies other than the operating frequency. Reference is made, for explanatory purposes, to an " expanded turnstile " array, Figs. 1 and 2 (not shown), comprising four sections-,- each having six dipoles displaced vertically and angularly by equal amounts. The Specification, as open to inspection under Sect. 91, also describes other " turnstile " arrangements. In one, dipoles arranged; a quarter-wave-length apart and in space quadrature are connected to corresponding points in a transmission line constituted by a hollow flag pole serving as the outer conductor and supporting an inner conductor, Figs. 1 and 2 (cancelled, not shown). In a modification, Fig. 4 (cancelled, not shown), the transmission line comprises two separate masts. In a further modification two transmission lines comprising four vertical masts are used, the phase of the energy in one line being displaced 90 degrees from that in the other, Fig. 5 (cancelled, not shown). This subject-matter does not appear in the Specification as accepted.