GB483449A - Improvements in or relating to navigation aiding radio transmitting installations - Google Patents

Abstract

483,449. Directive wireless signalling. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. Aug. 20, 1937, No. 22905. Convention date, Aug. 20, 1936. [Class 40 (v)] Relates to wireless transmitters of the overlapping- beam type in which two dipoles are bached by a common reflector and fed from the same H.F. source through branched feedlines. The invention consists in means for matching the dipoles to their feeders, and for preventing undesirable reaction between the feeders and aerials during periods when the latter are short-circuited, i.e. when producing divergent beams. If the dipole 11, Fig. 2, is connected to the feedline 10 at a point where it forms a capacitive load, this is counterbalanced by a variable " trombone " inductance 13. In Fig. 4, the surge impedance of the feeder 18 is represented by the straight line 20, and the resistance of the aerial 19 by the curve 21, and matching is secured by inserting an inductance at L or a capacity at C. In Fig. 5, the two dipoles 22, 23 are backed by a reflector P and fed from a common source S. The short - circuiting necessary to produce two diverging beams is effected at the points 24, 25, situated an odd number of quarter wavelengths away from the branching point 26, preferably by shunting the feeders by a timed circuit, the impedance of which can be varied from zero to infinity.