Orotron oscillation at 75 GHz

Principles of operation of the orotron, an electron tube device for the generation and amplification of millimeter waves, are discussed. A theory of operation is presented in which electrons interact with the electromagnetic field of the open resonator of the device, leading to bunching. A linear calculation allows the prediction of the electron beam current required to initiate oscillation of the device. The theory predicts a starting current of 34.5 mA and a tuning transconductance of 0.31 MHz/V for a device designed to operate at 75 GHz. The details of an experimental design based on the results of the theoretical calculation are given.