GB725628A - Improvements relating to variable phase-shifting networks - Google Patents

Abstract

725,628. Phase-shifting. METROPOLITANVICKERS ELECTRICAL CO., Ltd. June 26, 1953 [June 27, 1952], No. 17826/53. Class 38 (2). [Also in Group XL (c)] A variable phaseshifting network, particularly applicable to the phase modulation of a carrier wave, comprises two or more similar phase-shifting circuits arranged in cascade and fed from the wave source, a control or modulating voltage being applied to vary the phase characteristic of all the circuits so as to produce a resultant phase shift which is the sum of the individual phase shifts. Fig. 4 shows a system employing two similar phase-shifting networks 4, 5, each comprising two condensers 24, 25 in series in one lead from a source feeding carrier current through the networks to a load. An inductance coil 22 shunts each pair of condensers, and a coil 23 is connected between the condenser junction and the other carrier lead. The condensers may be of the type in which the capacity varies with the applied voltage. As shown, a modulating signal applied at the terminals 34, 35 appears across each condenser, the coils 22, 23 and the carrier choke 33 having negligible impedance at the modulating frequencies. The aerial or other load is connected at the points 29, 30 and an impedance 6 matches the line to the load. In Fig. 5, the modulation signal is applied at terminals 40, 41 to coils 37, 39 arranged to vary the inductance of the series and shunt coils 22, 23 of each unit 4, 5. The positions of the coils and condensers in the networks may be interchanged; and an additional condenser 26 may be connected across the coil 22.