GB611931A - Improvements in or relating to methods of and means for producing modulated ultra-short waves - Google Patents

Abstract

611,931. Magnetrons. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. March 12, 1946, No. 7746. Convention date, Feb. 6, 1945. [Class 39 (i)] [Also in Group XL (c)] Ultra-short waves transmitted by a waveguide are modulated by de-tuning a resonator coupled to the guide, the modulating-voltage being applied to a space-charge valve of the magnetron type, to vary the effective capacity in the resonator circuit. As shown, a wave generator E feeds a wave-guide G which is branched at Q to form two guides 1, 2 leading respectively to a radiating horn K and to an absorbing termination F1, R, P1. Coaxial-line resonators L1, L2 are coupled to the guides 1, 2 by condensers S, the outer ends being terminated by the cylindrical anodes and axial cathodes of magnetron valves M1, M2. Modulating voltage is applied in complementary or push-pull fashion to the condenser plates S and thus to the magnetron anodes. The magnetrons M1, M2 operate in a magnetic field of such strength that the space charge electrons resonate at a frequency close to that of the transmitted wave; under these conditions, the apparent capacity of the magnetrons varies rapidly with their anode potential, and in consequence of the de-tuning of the resonator L1, the wave transmission to the horn K is varied in the rhythm of the modulating voltage.