GB694646A - Improvements in or relating to frequency modulated very high frequency oscillator arrangements - Google Patents

Abstract

694,646. High-frequency phase changers. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. April 20, 1951 [June 27, 1950], No. 16063/50. Class 40 (viii). , [Also in Group XL (c)] Frequency modulation of an oscillator is linearized by coupling it to a transmission line of distributed impedance or wave-guide of a plurality of wavelengths long having near its load end a lumped impedance, e.g. a screw 3 adjustably projecting into the line or guide to produce reflection, and by adjusting the electrical length of the line or guide between the oscillator 1 and lumped impedance 3, as by a thin sheet of dielectric 5 pivoted at one end and projecting adjustably through a longitudinal slot 5a in the line or guide. Alternatively electrical length adjustment may be produced by a further screw 6, Fig. 2 (not shown), between the screw 3 and oscillator. The lumped impedance 3 may alternatively be a slot in the wave-guide. The line or guide may be fed from a reflex klystron, or continuous wave magnetron or from an oscillator with reactance valve modulator. The distance 1-3 between oscillator 1 and impedance 3 should be where # 9 is the guide wavelength, n is an ... integer which should be small for linearizing large frequency deviations but large enough to prevent excessive output power variation during correction, and # is a critical fraction. The screws 6, 3 may be mounted on a plate and jointly movable along a slot on top of the guide wall. The line or guide may be in series with the oscillator output or in parallel with it, Fig. 6 (not shown), in the latter case terminating in a dummy load. This assembly may be built into an oscillator. A plurality of correcting lines or guides may be used.