GB526036A - Improvements in or relating to radio direction finders - Google Patents

Abstract

526,036. Directive wireless signalling. SOC. FRANCAISE RADIO-ELECTRIQUE. March 6, 1939, No. 7324. Convention date, March 4, 1938. [Class 40 (v)] To allow the same directional aerial system, and the same length of feeders, to be used for receiving different wavelengths, one pair of spaced aerials A, B, C, D, Fig. 2 (connected in opposition to a receiver to give a high degree of directivity) are combined with a second pair of aerials A<SP>1</SP>, B<SP>1</SP>, C<SP>1</SP>, D<SP>1</SP>, which are connected additively to the receiver, so that they are substantially non - directional. The whole system is rotatable about a vertical axis O, V. The pick-up from the directional pair is fed at 1, 2, Fig. 3, to push-pull amplifiers L<SP>1</SP> 1 . L<SP>11</SP> 1 , and is combined in the circuit C3 with that from the non-directional pair via the leads 11, 21 through the output coil of an amplifier L2. A low-frequency voltage from a local source G and transformer T is fed across the grids of the amplifiers L<SP>1</SP> 1 , L<SP>11</SP> 1 , so as periodically to reverse the phase of the two signals. The same low-frequency voltage is also fed through a transformer T<SP>1</SP>, and a double diode V, to a centrezero indicator I. The latter is also supplied with the output current from the low-frequency amplifier R, and serves to show both the direction and sense of the incoming signals. The indicator I may be replaced by a relay which closes different contacts according to the direction of the received signals, so as to operate a servo-motor which keeps the aerial orientated along the bearing-line.