A self-excited drift-tube klystron frequency multiplier for use in generating millimeter waves

Theoretical and experimental considerations are presented in this paper for a self-excited frequency multiplier in which the fundamental oscillator is an integral cavity two-gap klystron and a harmonic resonator is placed at an appropriate position in the drift tube between the two gaps. This is a new device and it is called a drift-tube klystron frequency multiplier abbreviated as DTKFM. A general design procedure is given, based on both theoretical equations and experimental characteristics. Operation of the self-excited DTKFM with fundamental oscillations at 4 and 1 cm and harmonics at 1 cm and 5 mm respectively, is presented. The device is capable of generating larger CW output power at millimeter wavelengths than many existing devices.