GB424239A - Improvements in duplex radio aerial systems - Google Patents

Abstract

424,239. Wireless signalling ; aerials. AMY, ACEVES, & KING, Inc., 11, West 42nd Street, New York, U.S.A.-(Assignees of Amy, E. V., and Aceves, J. G. ; 11, West 42nd Street, New York, U.S.A.) May 31, 1934, No. 16252. Convention date, Dec. 22, 1933. [Class 40 (v)] Long and short wave signals are received alternatively or simultaneously on a common aerial through a down lead which is free from interference by local sources of induction. The whole of the aerial A, All is used for the long waves, the signal currents being transferred through a transformer T so that they flow serially through a double transmission line D, D1 to a branched coil T11 feeding the long-wave receiver R1, or to the coil T1111 feeding a combined long and short wave set R11. Short-wave signals are fed by direct coupling from the point B of the dipole aerial A, A1 through a condenser C and downlead D to the coupling-coil T1 of the receiver R (and to the parallel coupling-coil T111 of the receiver R11) and back through the return lead D1 to the point B1. The impedance of the coils T11 and T111 is sufficient to exclude these currents from the long-wave receiving circuits. The main aerial-to-earth circuit for the long-wave aerial is completed from a centre tapping on the transformer T, through the twisted downleads D, D1 in parallel to earth at G through a centre-tapped coil L3. Inductive " pick-up " currents pass through the downleads D, D1 in parallel, and are therefore balanced out in the receiving circuits. The secondary of the transformer T may be directly earthed through a third winding, which is screened by the leads D, D1 ; and auto-transformer coupling may be used. Separate aerials, set at right-angles, may be used for the long and short wave signals, Fig. 4, (not shown). If the input transformers to the sets are loosely coupled, different sets may be tuned to different frequencies on the same wave-band without mutual interference.