Systems sensitive to the direction of propagation of electromagnetic waves

摘要

537,389. Directive wireless systems. STANDARD TELEPHONES & CABLES, Ltd. Feb. 9, 1940, No. 2533. Convention date, March 7, 1939. [Class 40 (v)] The " sense " of an incoming signal, transmitted say, by an approaching aeroplane, is determined rapidly, i.e. without having continuously to oscillate the search-coil of an Adcock or other aenal, by operating a three-point switch 27, Fig. 7. In its upper position, the switch gives the usual " ambiguous bearing-line AA1, Fig. 1, and in the centre position rotates the figure-of-eight diagram 1, Fig. 2, through an angle of say 45 degrees to the position 2, and simultaneously converts it to cardioid form 3. In the lower position of the switch the cardioid 3 is reversed as shown by the dotted lines 4. The comparison of the signal intensity OB in the second switch position, with that OB1 in the third switch position, then gives a clear indication of the sense of the incoming signal.