GB590473A - Tuned circuit and system therefor - Google Patents

Abstract

590,473. Electric resonators; valve circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 22, 1944, No. 11921. Convention date, Sept. 26, 1942. [Classes 40 (iii) and 40 (v)] A tank circuit for use in an amplifier for waves of saw-tooth or other arbitrary shape, or in an oscillation-generator, comprises a coaxial or other transmission line which has a velocity of propagation independent of frequency, is an integral number of ftmdamental wave lengths long, and is closed upon itself so as to be resonant to harmonics as well as to the fundamental frequency, since'end effects are eliminated. The velocity of propagation is rendered independent of frequency by arranging that the usual transmission constants R, L, S, C shall be such that R/L=S/C, and uniformity is secured by using a number of small class A amplifiers 25, Fig. 4, evenly distributed around the endless resonator 5<11>. In this embodiment, the valves are excited in a phase relationship which is determined by a cathode beam B passing clockwise over target anodes P at such an angular speed that the resulting waves which travel clockwise round the resonator 5<11> are in additive phase for all the valves, while the waves which travel counter-clockwise cancel one another's effects, and owing to the endless form of the resonator, these conditions hold for harmonics as well as for the fundamental so that the wave-form is not distorted. The valves 25 are arranged to produce a sawtooth voltage, the condensers C being charged through resistances R until discharged rapidly through the cathode beam B. A second stage 25<1>, 25<111> of amplification may be used if necessary, the connections of the valves 25<1> being evenly spaced between those of the valves 25 so that the valve capacitances may be uniformly distributed. Waves of any desired form may be generated by suitably shaping the electrodes P. In an amplifier, Fig. 5 (not shown), for waves of arbitrary wave-form, the required phase relation between valves connected like the valves 25 to an endless resonator like the resonator 5<11> is obtained by connecting the grids of the valves to points evenly spaced along a transmission line which is reflectionlessly terminated and is fed with waves of the required form. In an oscillation generator, Fig. 6, the grid of each valve is connected to its plate through a #/2 path r, s, and the valves reinforce one another's oscillation for waves travelling-clockwise, but not for waves travelling anti-clockwise. In devices of the kinds described, lumped capacities may be connected between the valves in order to increase the uniformity of distribution of the capacity. Oscillations of any wave-form may be produced by arranging for different pairs of valves to develop different harmonics of suitable amplitude and phase. The resonator may be circular or may be folded. The line may be composed of continuous electrodes so as to have a continuously-distributed negative conductance as described in U.S.A. Specification 2,168,782.