GB592569A - Improvements in or relating to apparatus for generating or controlling high frequency electromagnetic waves - Google Patents

Abstract

592,569. Velocity - modulated tubes. WESTERN ELECTRIC CO., Inc. Aug. 20, 1943, No. 13641. Convention date, March 11, 1941. [Class 39 (i)] A high-frequency electron discharge apparatus comprises a cathode 5 from which an electron stream flows to anode 6 through a high-frequency input field enclosed in cavity resonator 1 and through an output field in resonator 2. These two fields are screened from each other by grids 9 and 11 and the electron transit time through the high-frequency input field lies between the period of a whole number of cycles and this period plus one-half a cycle. The flow of electrons is maintained so slow that they become density modulated in the input field. The screening permits the input portion to be treated as a diode and as set out in Specification 516,750, this can operate under space charge control at high-frequencies when the transit time is suitably chosen as above. The transit time through the output field is preferably less than the period of one cycle thereof. In a modification, the resonators 1 and 2 are provided with a common barrier wall and a grid of substantial depth replaces grids 9 and 11, this single grid exerting sufficient screening for some cases. In another case, however, an additional screening grid may be provided between grids 9 and 11. The input and output fields may each be confined within two grids in the electron stream and either the cathode or anode or both thus maintained outside the fields. Specifications 518,015, 523,712 and 541,477 also are referred to.