Nippon Electric Co., Ltd.

Hiroshi Kato

Takao Kageyama

A multi-cavity type velocity modulation tube, operable in the K-band above 10 GHz and having input, pre-buncher, buncher and output cavities which are respectively tuned to frequencies that are higher than the upper end of the operating pass band; near the upper end of the operating pass band and lower than the resonant frequency of the input cavity; higher than the resonant frequency of the input cavity; and within the operating pass band of the tube. The input cavity Q-value is lower than that of the prebuncher cavities. Preferably first and second prebuncher and first and second buncher cavities are provided, the second prebuncher and at least one of the bunchers are unloaded and the second prebuncher is tuned to a frequency in the vicinity of the lower end of the operating pass band. The design yields a low cost tube having a significantly improved gain-bandwidth product.

Wideband multi-cavity velocity modulation tube

In a four-cavity velocity modulation tube comprising an electron gun assembly, an input cavity, a pre-intermediate cavity, a post-intermediate cavity, an output cavity, a collector assembly and drift tubes interposed between adjacent ones of said cavities, said input cavity is tuned to the proximity of the lower end of the operating passband of said velocity modulation tube, said pre-intermediate cavity is tuned to the proximity of the upper end frequency of said operating passband, said post-intermediate cavity is tuned to a fundamental resonant frequency that is higher than the upper end frequency of said operating passband but lower than a frequency which is 1.6 times as high as the center frequency of said operating passband, the normalized length of all of said drift tubes being smaller than 90 degrees in terms of the reduced plasma angle, and the normalized length of the drift tube positioned between said pre-intermediate cavity and said post-intermediate cavity being larger than the normalized lengths of the other drift tubes.

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Tokyo, Japan

Hiroshi Kato