GB520821A - Improvements in or relating to directional radio transmitting devices - Google Patents

Abstract

520,821. Directive wireless signalling. SOC. INDUSTRIELLE DES PROCEDES LOTH. May 26, 1939, No. 15783. Convention date, May 30, 1938. [Class 40 (v)] A directional radio transmitting device for ascertaining direction, particularly in aerial navigation, comprises an open or closed frame aerial connected to an impedance at which is set up an alternating voltage of the frequency to be transmitted, two points situated on either side of the electrical centre of the impedance being alternately earthed. Differently directed beams overlapping one another are transmitted alternately so as to produce a guide plane in which both beams are received with equal intensity while outside this plane according as the receiver is situated to one side or the other of the guide plane the beam is received from one or the other direction. The alternating emission of the differently directed beams may be effected so that the modulation in the two different directions corresponds to the code forms of the letters " a," " n," or a dot-and-dash method may be employed. A transmitting device with a closed frame aerial is shown in Fig. 1. The radiating parts 1, 2 of the frame aerial are connected to an oscillatory circuit formed by a condenser 3 and a coil 4. In the coil is induced an alternating voltage from a generator 5 and amplifier 6. The coil 4 has two tappings 7, 8 which are alternately earthed by means of a switch 9 in the desired rhythm through a coil 10 and condenser 11. For use on short or ultra-short waves an open frame aerial formed by two vertical radiating devices 1, 2, Fig. 2, is employed. The tappings 7, 8 are connected to earth by the switch 9 without the interposition of a coil or condenser.