GB233346A - Improvements in or relating to directive aerials - Google Patents

Abstract

233,346. Levy, L. April 29, 1924, [Convention date]. Aerials and like radiating conductors; directive signalling. -A horizontal aerial is adapted to emit high-frequency radiation having a horizontal electric vector and concentrated into a pencil which is inclined to the horizon and lies in a plane which is normal to the aerial. Radiation so polarized is reflected from the Heaviside layer with minimum energy loss, so that " fading " is avoided, and atmospherics are eliminated from the receiving apparatus because their electric vector is vertical. The conductors are arranged in two groups in a horizontal plane and connected to opposite poles of the generator at their inner ends. In the embodiment shown in Fig. 3, the leads 9, 10 from the oscillation generator 11 neutralise one another's radiative effects, so that radiation takes place entirely from the horizontal meshwork shown, the parts 2, 3 of which are separated by chains of insulators. The height of the aerial should lie between #/8 and 5# /8 for a wave length #. Stationary waves are formed in the meshwork in two dimensions, the length from 5 to 7 being equal to half a wave length while the length from 5 to 5<1> is equal to an integral number of quarter wave-lengths. In a modification (not shown) the meshworks 2, 3, are each replaced by three parallel wires of length #/4, the lengths of the leads 9, 10, being #/2. A reflector may be provided comprising a wire placed on the ground and adapted to give an electric image of the currents in the aerial; or plane vertical reflectors may be arranged adjacent to the aerial. The receiving aerial may be a parallel horizontal aerial, elevated or at ground level, but owing to the inclination of the magnetic field a. vertical aerial or a horizontal aerial at right-angles to the former may be employed. Or the receiving aerial may be a horizontal frame aerial, or a vertical frame aerial parallel to the transmitting aerial. The Specification refers to a known arrangement, in which a vertical transmitting aerial is several wave-lengths long. The leads from aerial to earth may contain impedances, or may comprise interrupted lengths of conductor overlapping or placed end to end.