GB627689A - Wireless antenna - Google Patents

Abstract

627,689. Aerials. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 21, 1946, No. 15906. Convention date, May 4, 1942. [Class 40 (vii)] An aerial having substantially uniform horizontal directivity but with a vertical directivity varying with horizontal direction, is formed by cutting a metal cone by two pairs of planes 6, 8; 8, 10, and 12, 14; 14, 16, Fig. 1, so as to produce pairs of intersecting hyperbolae 26, 28; 34, 36, Fig. 7, two such cones 18, 20 being mounted with their truncated apices facing one another. The construction is stated to be particularly suitable for use on ships to provide substantiallyuniform vertical directivity during rolling and pitching. Alternatively, the cone may be cut by pairs of planes 54, 56; 56, 58, and 12, 14; 14, 16, and in this case the former pair of planes may be occupied by metal sheets 72, 74, Fig. 3, acting as reflectors. Such a " half-aerial " has a horizontal directivity of only 180 degrees and two such " half-aerials '' may be mounted on opposite sides of a ship. The spacing of the apices of the cones may be variable, e.g. by mounting the conical surfaces in slots 80 in the reflecting plates. The aerial is fed by a coaxial line, of which the outer conductor 24 is connected to one cone and the inner conductor 22 enters into the apex of the other, in which it is terminated in a matching impedance comprising an adjustable short-circuiting disc 27. The cones from which the aerials are cut may have circular or eliptical bases.