共查询到20条相似文献,搜索用时 15 毫秒
1.
对曲折圆形槽波导新型慢波系统的高频特性进行了研究,通过理论分析和数值计算,得到了它的色散曲线和耦合阻抗表达式,并分析了结构参数变化对色散特性和耦合阻抗的影响。研究表明:当周期变小时色散减弱,耦合阻抗增加;而增大直波导长度时色散变弱,但同时耦合阻抗也会下降。因此较小的周期有利于改善曲折圆形槽波导慢波电路的高频特性。鉴于这种电路的耦合阻抗较低,可以适当地减小直波导长度来提高耦合阻抗。曲折槽波导结合了曲折波导散热能力强、色散特性好、容易加工和槽波导单模工作、低损耗、大尺寸等优点,在毫米波及亚毫米波段的行波管中具有较好的发展前景。 相似文献
2.
Shunkang Liu 《International Journal of Infrared and Millimeter Waves》2000,21(9):1489-1493
A significant advantage of the folded wave traveling wave tube (TWT) is simple coupling structure. In millimeter wave band, owing to higher frequency, linear double taper can be used as impedance transformer. The design method and calculation results for the folded waveguide TWTs in K-band are given. 相似文献
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A three-dimensional (3D) nonlinear theory of travelling wave tubes (TWTs) is developed, which includes a fundamental radio frequency (RF) and harmonics. When the instantaneous bandwidth exceeds an octave, the harmonic is generated and the mutual coupling between the harmonic and the fundamental RF can be observed in TWTs due to nonlinear interaction between the electron beam and the RF. At low frequencies the harmonic has an obvious effect.Based upon Tien‘‘s disc model, a plastic 3D super-particle model is proposed to improve the nonlinear analysis of TWTs.Numerical results employing a periodic magnetic focusing field are presented. 相似文献
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将周期性慢波结构中的单元结构等效为一个三端口网络,利用高频结构模拟软件确定等效模型的参数,由此建立了一种通用的慢波结构等效模型.该方法不需要进行复杂的电路等效,直接由高频软件得到通道内场分布,因此较解析方法简单,又不像等效线路模型那么烦琐.基于该三端口网络模型,建立了适用于折叠波导行波管的一维注波互作用非线性理论模型,编写了数值计算程序,对一支折叠波导行波管进行了模拟.该理论模型模拟的结果与实验结果误差小于10%.该理论模型可以用于指导新型折叠波导行波管的设计及非线性模拟研究. 相似文献
6.
A slow-wave structure (SWS) with two opposite gratings inside a rectangular
waveguide is presented and analysed. As an all-metal slow-wave circuit, this
structure is especially suited for use in millimetre-wave travelling wave tubes
(TWTs) due to its advantages of large size, high manufacturing precision and good
heat dissipation. The first part of this paper concerns the wave properties of this
structure in vacuum. The influence of the geometrical dimensions on dispersion
characteristics and coupling impedance is investigated. The theoretical results show
that this structure has a very strong dispersion and the coupling impedance for the
fundamental wave is several tens of ohms, but the coupling impedance for --1 space
harmonic wave is much lower than that for the fundamental wave, so the risk of
backward wave oscillation is reduced. Besides these, the CST microwave studio is
also used to simulate the dispersion property of the SWS. The simulation results
from CST and the theoretical results agree well with each other, which supports the
theory. In the second part, a small-signal analysis of a double rectangular
waveguide grating TWT is presented. The typical small-signal gain per period is
about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4\%. 相似文献
7.
Shunkang Liu 《International Journal of Infrared and Millimeter Waves》1999,20(10):1749-1755
A computation technique for gain, efficiency and output power in broadband millimeter wave helix TWTs from their dimensions is described. The computed results by modeling are good agreement with experimental measurements. It is shown that the method is fast and useful accuracy. It can be used as engineering design for MMW TWTs. 相似文献
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Understanding the generation and growth of nonlinear harmonic (and intermodulation) distortion in microwave amplifiers such as traveling wave tubes (TWTs), free electron lasers (FELs), and klystrons is of current research interest. Similar to FELs, the nonlinear harmonic growth rate scales with the harmonic number in TWTs. In klystrons, the wave number scaling applies to the nonlinear harmonic bunching and associated nonlinear space-charge waves. Using a custom-modified TWT that has sensors along the helix, we provide the first experimental confirmation of the scaling of nonlinear harmonic growth rate and wave number in TWTs. These scalings of a nonlinearly generated harmonic mode versus an injected linear harmonic mode imply that suppression by harmonic injection occurs at a single axial position that can be located as desired by changing the injected amplitude and phase. 相似文献
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翼片加载螺旋线慢波结构广泛应用于大功率、宽频带行波管中。首次将考虑螺旋带径向厚度的螺旋带模型应用于翼片加载螺旋线慢波结构,将离散的夹持杆等效为一系列连续的介质层,各层取不同的径向相位常数,得到了实用的色散方程和耦合阻抗表达式。利用导出的方程对实际行波管的螺旋慢波结构进行计算,计算结果与测量结果具有良好的一致性。分析了螺旋带厚度、介质分层数以及外壳半径对计算结果的影响,结果表明考虑螺旋带厚度能大幅提高计算精度。 相似文献
10.
Shunkang Liu 《International Journal of Infrared and Millimeter Waves》2000,21(7):1097-1101
The feature of the ring-loop slow wave structure is high coupling impedance and low harmonic wave components. Therefore ring-loop traveling wave tube (TWT) has advantages of high gain, small dimension, higher operating voltage and less danger of the backward wave oscillation. But calculation of the ring-loop is rather difficult. Here on basis of calculation of dispersion and impedance, a fast estimation of interaction efficiency, output power and saturated gain for Ka-band ring-loop TWT are given. 相似文献
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对几种用3维MAFIA仿真软件以及利用其准周期边界条件和后处理模块计算耦合腔行波管慢波结构的色散和耦合阻抗等冷测特性的方法进行了讨论,另外还对两种阻抗_总阻抗和Pierce耦合阻抗的定义进行了充分讨论。考虑到休斯结构耦合腔行波管的电子是与耦合腔慢波结构的负一次谐波发生作用和耦合阻抗应该是电子注截面上的平均值等,指出总阻抗和Pierce耦合阻抗之间相差一个因子,考虑了这个修正因子之后,其结果将更接近实际情况。用这些方法计算耦合腔行波管的冷测特性,得到了与实验冷测值十分接近的结果。 相似文献
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利用CST Microwave Studio 计算双排矩形梳状慢波结构的色散并据此确定了0.22 THz左右频段(D波段)行波管用慢波结构的尺寸参数。将相速再同步技术应用于基于双排矩形梳状慢波结构的D波段行波管中,用CST PIC模拟计算了4例具有不同周期构型的D波段行波管。结果证实:对于无集中衰减器的D波段行波管,在218~232 GHz范围内,相速再同步技术使得输出功率从10~13 W提高到19~28 W,电子效率从1.4%~2.2%提高到2.6%~3.9%;对于具有集中衰减器D波段行波管,在218~232 GHz范围内,相速再同步技术使得输出功率从8~16.8 W提高到32~41 W,电子效率从1.5%~2.8%提高到4.4%~5.7%。此外,无论行波管有无集中衰减器,相速再同步技术都明显改善了行波管的增益平坦度。 相似文献
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Liu Shunkang 《International Journal of Infrared and Millimeter Waves》1994,15(4):769-773
A rectangular coupled cavity slow wave structure is a new type of circuit for high power millimeter wave TWTs in recent years. Matching characteristics of trasition between rectangular coupled cavity and waveguide are calculated by equivalent circuit method. The results obtained by this method are compared with experiments and it is shown that useful accuracy can be obtained. 相似文献
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Shunkang Liu 《International Journal of Infrared and Millimeter Waves》2000,21(6):915-920
The characteristics of two kinds of bifilar helix circuit are discussed in this paper. One is alike wound bifilar helix and another is contrawound bifilar helix. Alike wound bifilar helix is often used in O-type backward wave tube (BWO). Owing to wider operating bandwidth, higher interaction impedance and large dimensions, the contrawound helix is suitable for broadband millimeter wave traveling wave tube (MMW TWT). 相似文献
18.
Shunkang Liu 《International Journal of Infrared and Millimeter Waves》2001,22(2):309-314
The power capability of millimeter wave coupled cavity traveling wave tube (CCTWT) is larger than other type TWTs, but the operating bandwidth is narrow. Two methods (staggered bandwidth and coalescent mode design) of expanding to the CCTWT in NMW are described. The simple calculation method for realizing coalescent mode is given. 相似文献
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Mukesh Kumar Alaria A. K. Sinha A. Bera V. Srivastava 《International Journal of Infrared and Millimeter Waves》2008,29(12):1083-1090
The main objective of the paper is to make an efficient design of the input and output coaxial coupler for a helix TWTs. An
approach has been developed for the efficient design and analysis of the coaxial couplers in the practical situation. Normally
multi-section impedance transformer approach is used for any wide band coupler. For a space helix TWT, coupler should be wide
bandwidth and small size. In this case coupler is matched with helix slow wave structure and the standard 50-ohm connectors.
The simulated return loss (dB) profile for different type of couplers is obtained by using Ansoft HFSS, CST microwave studio
and compares those with experimental results. The tip loss design at sever ends for the input and the output section has been
also optimized. 相似文献