GB412500A - Improvements in or relating to radio transmitting installations - Google Patents

Abstract

412,500. Impedance networks. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London. -(Assignees of Bird, L. T. ; 211, St. Sacrament Street, Montreal, Canada.) Dec. 19, 1933, No. 35718. Convention date, April 22. [Classes 40 (iii) and 40 (v).] When a transmitter is connected to an aerial by a feeder, overloading of the transmitter due to initial mismatching of the aerial tuning and coupling device is .presented by the use during adjustment of a resistance network which serves both as a dummy load and as a bridge for testing the impedance of the aerial. The transmitter is connected through a feeder to the terminals T1, T2, and so to a network composed of resistances as shown in Fig. 3, where each resistance is equal to the characteristic impedance of the feeder, and during adjustment of the transmitter the galvanometer branch G is broken while a further resistance, equal to each of the others, is connected across the terminals H1, H2 (Fig. 2, not shown). Under these conditions the network is matched to the feeder at terminals T1, T2. The aerial is next connected across terminals H1 and H2 and its tuning and coupling device is adjusted until the galvanometer G indicates that the bridge is balanced. Finally the aerial is connected directly to the feeder at terminals T1, T2. The resistances shown as separate may be replaced by a smaller number of resistances having an equivalent effect (Fig. 1, not shown).