GB727527A - Improvements in or relating to antennae - Google Patents

Abstract

727,527. Aerials. SIEMENS & HALSKE AKT.-GES. Feb. 27, 1953 [March 3, 1952], No. 5610/53. Class 40 (7). An antenna having a uniform radiation characteristic over a wide angle in predetermined plane consists of a plurality of like dipoles arranged in the plane around a support and each provided with a reflector, the ratio of the length to the diameter of the dipoles being chosen so as to provide the required uniform characteristic and the dipoles being less than the working wavelength long. In one embodiment, a square support 1 carries dipole pairs 2, 3; 4, 5; 6, 7; and 8, 9 on its four sides and the dipoles are backed by plane reflectors 10, 11, 12 and 13. The dipoles are supported from the reflectors and the reflectors supported and spaced from the mast by tubes 22, 23, 24 and 25 in which the feeders are located. Dipoles shorter than a full wavelength to match the feeders in impedance are used and a ratio of length to diameter between 10 and 25 and normally, between 15 and 20 is stated to be satisfactory to give the required pattern. With such values of the ratio the antenna is suitable for a frequency band of television width. In a further embodiment (Fig. 2, not shown), basic antennµ of the general form shown in Fig. 1, but with the length of the dipoles and plane of the reflectors not parallel to the sides of the support, are stacked one above the other and displaced angularly relative to each other in order to provide a pattern approaching more closely to the circular. A number of dipoles may be associated with the same feeder in this arrangement.