Annular Circuits for High-Power, Multiple-Tube, Radio-Frequency Generators at Very-High Frequencies and Ultra-High Frequencies

A new type of cavity suitable for excitation by a plurality of negative grid tubes in phase is described. In such a generator, which may be either an amplifier or an oscillator, the efficiency is independent of the number of tubes, and very large sizes are possible, limited only by the occurrence of unwarranted modes. This limit has not yet been reached in practice. The upper frequency limit is the same as that for an individual tube in an optimum circuit. All forms of modulation may be used.