GB215787A - - Google Patents

Abstract

215,787. British Thomson-Houston Co., Ltd., (Assignees of Alexanderson, E. F. W.). May 11, 1923, [Convention date]. Addition to 187,986. Directive signalling; thermionic heterodyne receivers.-Relates to highly-directional receiving apparatus similar to that described with reference to Fig. 3 of the parent Specification in which rectified heterodyne currents from two mutually perpendicular directional aerials are coupled respectively to the grid and plate circuits of a thermionic valve, a phase rotator and audio-frequency tuned circuit being provided on the grid side while a telephone or like receiver without a high-tension battery is inserted in the plate circuit. No signal is heard unless the grid and plate potentials agree in phase, and the device is consequently highly directional. The present Specification describes the use of a vertical aerial 12, Fig. 1, coupled to the plate circuit in series with the loop aerial 13, the resulting directional effect being represented by the polar curve A, Fig. 3. The loop aerial, with polar curve B, is also coupled to the grid circuit, and the resultant effect on the receiving apparatus 17 varies with direction as shown by the shaded curve C, which is similar to that given by a wave antenna one wave-length long. Two such systems may be combined by applying the oscillations derived from them to the grid and plate respectively of a third similar system. Or a wave antenna may be coupled to the plate circuit while a loop antenna is coupled to the grid circuit. The Specification as open to inspection under Sect. 91 (3) (a) comprised also the subject-matter described with reference to Figs. 3 and 4 of the parent Specification. This subject-matter does not appear in the Specification as accepted.