GB543337A - Antenna systems - Google Patents

Abstract

543,337. Aerials. STANDARD TELEPHONES & CABLES, Ltd. Sept. 30, 1940, No. 14736. Convention date, Jan. 26. [Class 40 (v)] Relates to aerials for short-waves giving maximum radiation in the equatorial plane, of the kind comprising several co-linear half-wave antennae energized in the same phase, the opposite phase being eliminated by folding the antenna wire; and consists in forming the folded portions by attaching to the antenna at half-wave intervals one or more sleeves each a quarter wave long. As shown in Fig. 1B the quarterwave sleeves 2 are attached to the aerial 1 at points 3 half a wave-length apart, so that their inner surfaces form with the enclosed portions of the aerial a folded half-wave line, from which the radiation is suppressed. The aerial thus comprises in effect a number of half-wave aerials all energized in the same phase as indicated by the current distribution curves 16. Connections are made to the wave source or receiver 4 at the base of the aerial 1 and at a point on the lowermost sleeve 2. In a modification the aerial 1 is tubular and is fed by an internal concentric line the inner member of which is connected by short radial leads to alternate sleeves (Fig. 2, not shown). The aerial may be in the form of a tapered lattice structure and the sleeves may comprise openwork cage structures (Figs. 3A and 3B, not shown). The aerial shown in Fig. 4B comprises a series of superposed quarter-wave tubes decreasing in diameter towards the top, and with alternate tubular sections enclosed by sleeves 42. Alternate sleeves are connected by radial leads 47 to an axial line 45 which together with the inner surface of the tubes forms a con centric feeder. The transmitter or receiver is connected to a low-impedance line 51 which is matched with the aerial impedance by connecting its inner wire 53 to a point 54 situated a suitable distance above the end-plate 50 of the aerial structure.