Publication Date


Document Type


First Advisor

Shin, Young-Min

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Physics


Electrical engineering; Physics; Amplifiers; Traveling-wave; Electrical engineering; Physics


In a non-relativistic plasma regime, an electron beam with a few tens of keV is capable of producing a powerful coherent radiation when it is synchronized with a backward or forward electromagnetic wave traveling along a periodic slow wave structure with a metal corrugation or a dielectric. In particular, the forward synchronization efficiently converts the power lost from the electron beam, while being decelerated, to a RF power of forward traveling wave, which is the basic principle of RF traveling wave amplifiers (TWAs). TWAs are widely used with solid-state drivers in microwave power modules (MPMs) for long distance communications and remote sensing in military and civilian areas. However, practical application of conventional TWAs to remote communication has been fairly limited below Ka-band (∼ 40 GHz) for rapid saturation of RF power-gain from a single-stage beam-wave synchronization with an increase of operating frequency. For the past two years, we have studied phase-velocity tapering concept for extended beam-wave synchronization of a high frequency (V-band: 71 -- 76 GHz) TWA structure in the collaborative research project with an industrial partner and Air Force. Our analysis on the Pierce small signal gain theory and particle-in-cell (PIC) simulations indicates that the designed structure with the extended phase-velocity matching produces unprecedented level of power (60 - 80 Watts) and bandwidth (7 %) with exceptionally large efficiency (> 8%) and gain (∼ 30 dB) from a dc elliptical beam (10 keV and 100 mA) at V-band. This paper will discuss details of the research project, including system design and RF transmission-test.


Advisors: Young-min Shin.||Committee members: Omar Chmaissem; George Coutrakon; Bela Erdelyi.


84 pages




Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type