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| Simulation Investigation of Backward Wave Oscillation of Millimeter-wave TWT |
| Lu De-jian①② Wang Zi-cheng① Liu Pu-kun① |
| ①(Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China) ②(Graduate University of Chinese Academy of Sciences, Beijing 100039, China) |
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Abstract HFSS is used to simulate helical, contrawound helix and coupled-cavity Slow-Wave Structures(SWS), which work in Ka-band, to investigate the backward-wave oscillation of millimeter-wave TWT. The results show that, space harmonics, which axial space harmonic number and azimuth space harmonic number are unequal, are evident in helical SWS, the SWS runs a risk of backward oscillation near the π mode. Relatively, contrawound helix shows excellent ability in restraining backward oscillation by improving interaction impedance and the normalized frequency which can work without backward oscillation. And coupled-cavity should avoid working around those frequencies where phase shifts per cavity are π or 2π.
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Received: 30 March 2007
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Corresponding Authors:
Lu De-jian
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2008, Vol. 30 
