GB1204929A - Improvements in or relating to aerials - Google Patents

Abstract

1,204,929. Aerials. GENERAL ELECTRIC and ENGLISH ELECTRIC COMPANIES Ltd. 14 April, 1969 [23 Feb., 1968], No. 9031/68. Heading H4A. In a wide-band aerial comprising two flat interleaved spiral elements 1, Fig. 1, connections to the outer ends of said elements are made by two flat conductors 4, the elements and the conductors being substantially coplanar. As described, the conductors 4 extend radially to a semicircular conductor 3 which provides a balun and which is concentric with the elements 1. Coupled sections 6 are provided, each being in the form of an end-connected pair of closely spaced parallel lengths of conductor extending radially inwards from the conductor 3, and a terminal 5. The elements and the conductors are formed by a printed circuit technique on one side of a disc 2 of dielectric material, the other side of which has a conductive coating except for a circular area in register with the elements 1. A second similar disc of dielectric material, which is secured to the disc 2 over the elements and conductors, is provided on its outward facing side only with a conductive coating, except for a circular area in register with the elements 1. The inner conductor of a coaxial connector is connected to the terminal 5 and the outer conductor thereof is connected to the outer conductive coatings of the dielectric material discs (Fig. 2, not shown). The inner ends of the elements 1 are connected by a resistive impedance, for example a thin coating of absorptive paint. The aerial may be placed over a hollow cylindrical resonant cavity with the area occupied by the spiral elements simulating an end wall, to enforce radiation on one side only of the aerial. In another embodiment the outer ends of the spiral aerial elements are extended by conductors which run tangentially instead of radially, thereby avoiding rightangled bends (Fig. 3, not shown).