GB424698A - Improvements in or relating to directional aerials - Google Patents

Abstract

424,698. Directive wireless signalling. CORK, E. C., 53, Stoneleigh Drive, Worcester Park, Surrey, and WHITE, E. L. C., 32, The Rise, Hillingdon, Middlesex. Oct. 23, 1933, No. 29357. [Class 40 (v)] The dimensions of an inverted-U aerial are chosen so that it receives or transmits most readily on a predetermined wavelength in one prescribed direction and has a minimum reception or radiation in another prescribed direction at an angle of less than 180‹ to the first direction. As shown, the aerial comprises earthed vertical members 1, 2, Fig. 1, and a horizontal member 3, the member 1 having the transmitter or receiver impedance 5 connected therein and the member 2 having its end terminated by a resistance 4 equal to the characteristic impedance of the aerial. It is shown that if L is the length of the vertical portions and B the length of the horizontal portions, # the wavelength in question and alpha and # the angles between the required maximum and minimum directions respectively and the plane of the aerial then the equations L+B (1-cos alpha) = (m+¢)# and L+B (1+ cos #) = n# should be simultaneously satisfied, m and n being integers. The physical length of the members 1, 2 may be reduced by folding as shown in Fig. 4, which shows an upright-U portion 11, 21, 31, arranged below and of the same dimensions as the inverted-U portion, the transmitter or receiver 9 being coupled between the pair 1, 1<1> of vertical members, the other pair 2, 2<1> being joined by a resistance 10.