GB597998A - Improvements relating to ultra-high-frequency electron-discharge apparatus - Google Patents

Abstract

597,998. Velocity-modulated tubes. SPERRY GYROSCOPE CO., Inc. Aug. 27, 1945, No. 22036. Convention date, Aug. 25, 1944. [Class 39 (i)] In an ultra-high-frequency electron discharge apparatus, a beam of electrons from a gun 14 is velocity modulated on passing through a cavity resonator 11 excited by an ultra-highfrequency field through input loop 27, is density modulated in drift tube 19 and has energy extracted from it in resonators 16 and 21, both excited to the input frequency and coupled by a common grid 18 and by a phase-shifter 33 connected between the coupling lines 28 and 31. The resonators 11, 16, 21 are individually tunable by means of elastic membranes 36, 37, 38 and screws 44, 47, 48 engaging plates 39, 41, 42 and 43 rigidly connected to the outer wall of resonator 11, drift tube 19, the outer walls of resonators 16, 21 and the supports of grid 23 respectively. The distances between the pairs of grids 12, 13 ; 17, 18 ; 18, 23 can thus be varied according to the frequency required. Tension springs 51 are coupled between the members 39, 43 to take up backlash and members 41, 42, 43 are suitably apertured to give free passage of the spring and permit access to the screws 47 and 48. The phaseshifter 33 is adjusted to phase delay the energy travelling from resonator 16 to 21 by the same phase-shift as is produced by the transit time of the electron bunches between the two output resonators or differing therefrom by an integral number of cycles, and all resonators are tuned to the input frequency. Alternatively, one resonator may be tuned above the frequency of the electron stream while the other is tuned below by the corresponding amount and the phase-shifter dispersed with. Three or more output resonators may be similarly coupled together. In a modification (not shown), the input may be into a resonator tuned to a frequency sub-harmonically related to that of the output resonators.