一种新型微带曲折线慢波结构的设计

设计了一种新型微带曲折线慢波结构,该结构采用双介质杆支撑式的V型平面曲折线慢波电路。利用电磁场仿真软件HFSS对这种新型结构和传统微带曲折线慢波结构进行了分析比较,研究结果表明,新型微带曲折线慢波结构在不改变色散强弱的情况下,工作频段向高频端拓展且耦合阻抗有了很大提高,可以更好地工作在短毫米波段。并仿真分析了结构参数对高频特性的影响,所获得的仿真结果为器件的粒子模拟及计算慢波结构的工作效率奠定了基础。     

螺旋带径向厚度对色散和耦合阻抗的影响

该文将有限厚度的实际螺旋带等效为存在无限薄螺旋带的等厚真空层,从场分析和软件模拟两个方面研究了等效慢波结构的色散特性和耦合阻抗.将理论计算、软件模拟和实验测试结果进行了比较,结果表明,用真空层等效有限厚度的实际螺旋带时,将无限薄螺旋带置于等厚真空层的中央,其螺旋慢波结构的色散特性和耦合阻抗的理论计算、软件模拟和实验测试结果三者取得了很好的一致.     

CST MWS软件模拟三维螺旋线慢波结构

本文介绍了用CST MWS软件的周期边界条件计算行波管螺旋线慢波结构的色散和耦合阻抗等冷测特性的方法,用采取螺旋带模型的理论分析计算结果和实验测试值加以验证,取得了比较一致的结果;并应用这种MWS的模拟方法和螺旋带模型的计算方法分析了具有扇形和T形夹持杆慢波结构的冷测特性,结果表明,相速和耦合阻抗都随着扇形角度的增大而减小,随着T形窄端宽度的增加而减小,随着T形窄端高度的增加而增大.     

毫米波螺旋线行波管慢波系统高频损耗

基于夹持杆分层螺旋带模型和三维电磁场分析研究了毫米波螺旋线行波管慢波系统的导体和介质损耗。螺旋带模型中介质损耗考虑为纵向传播常数的虚部,给出螺旋带中电磁场的解析解,导体损耗由螺旋线和管壳表面的面电流不连续性获得。三维电磁场分析通过本征模法,求解单周期结构的品质因数和周期储能获得有限导电率导体和夹持杆陶瓷损耗角带来的慢波系统高频损耗。结果表明,毫米波段螺旋线的导体损耗和夹持杆的介质损耗远大于管壳导体损耗,介质损耗与陶瓷损耗角呈线性关系,对高频损耗的影响不可忽略。     

螺旋慢波系统高频特性的计算机仿真

介绍了用德国CST(Computer Simulation Technology)公司提供的微波工作室MWS(Microwave Studio)4．2软件模拟计算螺旋线慢波系统的色散特性和耦合阻抗的理论方法。通过对矩形夹持杆支撑螺旋慢波结构的模拟计算,与测试结果相比色散特性的平均模拟误差为1．5%左右,耦合阻抗的平均误差为0．3％左右;相比于MAFIA仿真,计算精度更高,计算时间更短。     

电子器件

0309376翼片加载螺旋线慢波结构的螺旋带模型[刊]/张勇//强激光与粒子束.—2002,14(6).—887～891(K)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,建立了翼片加载螺旋线慢波结构的螺旋带模型,得到了实用的色散方程、耦合阻抗和衰减常数的表达式。利用导出的方程对实际行波管螺旋慢波结构进行计算,井与测量结果和导电面模型进行了比较,计算结果与测量结果具有良好的一致性。分析了不同管壳半径对色散特性的影响。参8     

一种基于LTCC技术的螺旋电感带通滤波器

本文提出一种新型的基于低温共烧陶瓷技术(LTCC)的螺旋电感带通滤波器.滤波器的设计是利用螺旋电感的自谐振和谐振单元间的电磁耦合来实现.通过HFSS仿真和等效电路分析,对滤波器结构进行了优化分析.这种滤波器具有体积小.结构布局灵活的优点,可以很好的满足器件埋置的要求.     

行波管慢波系统的新进展—全金属慢波结构

作为大功率，中等带宽行波管用慢波线，全金属慢波系统具有突出的优越性，尤其适合在毫米波行波管中的应用。本文论述了各种新型全金属慢波结构的发展动态，着重介绍了螺旋槽慢波线的基本理论，提出了在我国开展这一领域研究的必要性。     

螺距对螺旋慢波系统色散和耦合阻抗的影响

螺距是慢波系统的一个重要参数,直接影响螺旋慢波系统的色散特性和耦合阻抗.严格求解螺距对慢波系统色散和耦合阻抗的影响是不方便的,而通过计算机模拟可以方便快速地研究螺距对慢波系统色散和耦合阻抗的影响.模拟结果表明,对于工程项目当螺距变化小于4%时,螺距对色散和耦合阻抗的影响是很小的.     

理论分析毫米波螺旋线行波管慢波系统导体和介质损耗

该文基于夹持杆分层螺旋带模型和3维电磁场模型分析,详细研究了毫米波螺旋线行波管慢波系统的导体和介质损耗。螺旋带模型中介质损耗考虑为纵向传播常数的虚部,给出电磁场的解析解,导体损耗由螺旋线和管壳表面的面电流不连续性获得。3维电磁场模型分析通过本征模法,求解单周期结构的品质因数和周期储能,获得有限导电率导体和夹持杆陶瓷损耗角带来的慢波系统高频损耗。结果表明,毫米波段螺旋线的导体损耗和夹持杆的介质损耗远大于管壳导体损耗,介质损耗与陶瓷损耗角呈线性关系,对高频损耗的影响不可忽略。     

Analysis of the Dispersion Characteristic and Interaction Impedance of a Tape Helix Slow Wave Structure with Novel Supporting Mode

In order to enhance the power capability of the helix travelling wave tube, a novel tape helix slow wave structure (SWS), which is supported by helically arrayed radial dielectric-support posts, is developed. Each dielectric post can be easily brazed with the tape helix and the metal envelope by means of a special soldering. This kind of supporting mode can protect the dielectric supporting posts from being broken by the thermal stress in the case of high temperature. A hybrid model is set up in consideration of the influences of both the radial thickness of the tape helix and these discrete dielectric-support posts. The dispersion equation and interaction impedance of the helical SWS are obtained. The calculated results using this hybrid model presented in the paper show good agreements with the HFSS simulation results. All the results presented here can provide a good basis for designing the novel tape helix SWS.     

毫米波行波管返波振荡的仿真研究

该文利用HFSS仿真了工作在Ka波段的螺旋线、反绕双螺旋线及耦合腔等慢波系统,通过傅里叶分析得到空间谐波,进而分析和比较了上述慢波系统的返波振荡特性.结果表明:螺旋线慢波系统中出现明显的角向谐波次数和轴向谐波次数不相等的窄问谐波分量,在π模附近,有产生返波振荡的危险:而反绕双螺旋线通过提高基波耦合阻抗及可工作的归一化频率来提高了抑制返波振荡的能力;为了避免返波振荡,耦合腔工作频带的选择应尽可能远离单腔相移为π,2π的频点.     

A Simple Equivalent Circuit Analysis of the Dielectric Loss in a Helical Slow-Wave Structure of a Traveling-Wave Tube

The electromagnetic field analysis of a helical slow-wave structure (SWS) is carried out based on a tape-helix model incorporating the effects of space-harmonic propagating modes and the surface current on the helix over the actual metallic area of the tape. Using this analysis, closed-form expressions are derived for the shunt capacitance per unit length and the shunt conductance per unit length of the transmission-line equivalent circuit of the structure. The analysis is interpreted for the circuit attenuation constant contributed by the loss of the dielectric helix-support rods. The analysis is accurate, amenable to easy computation, and validated against published results. The analysis is subsequently used for investigating the dielectric loss in an SWS due to the backward-wave ($-$1) space-harmonic mode of propagation.      

Rigorous tape analysis of inhomogeneously-loaded helical slow-wavestructures

The inhomogeneously-loaded helical slow-wave structure is field analyzed by azimuthally smoothing out the discrete supports into a number of continuous dielectric tube regions of appropriate permittivity values. The analysis is made rigorous by removing the usual approximation of considering the radial propagation constant to be the same in the different structure regions; moreover, a tape-helix instead of a simpler sheath-helix model has been used to consider the space-harmonic effects. This renders the present analysis more general, accurate and capable of dealing with a wide range of structure parameters, and particularly makes it valid for large values of helix pitch angle, inhomogeneity and separation between the helix and the metal envelope of the structure. Further, structured expressions amenable to easy computation are presented with the help of the recurrence relations for various structure regions, and methods to use them effectively in an iterative cycle for the desired accuracy are suggested. The developed analytical expressions have also been checked by seeing that they pass on, as special cases, to those obtained earlier by making simplifying assumptions. In this comparison, care has been taken to account for the helix tape thickness by considering a free-space gap equal to the difference between the mean helix radius and the inner radius of the dielectric helix support. The results for the propagation characteristics of an inhomogeneously-loaded helical structure presented here are rather general and can readily be used for the structure design, performance evaluation, and control of any space harmonic of interest in a practical device     

Analysis of Helix Slow Wave Structure for High Efficiency Space TWT

This paper describes the analysis of helix slow-wave structure (SWS) for a high efficiency space traveling wave tube that is carried out using Ansoft HFSS and CST microwave studio, which is a 3D electromagnetic field simulators. Two approaches of simulating the dispersion and impedance characteristics of the helix slow wave structure have been discussed and compared with measured results. The dispersion characteristic gives the information about axial propagation constant (Beta). Which in turn yields the phase velocity at a particular frequency. The dispersion and impedance characteristics can be used in finding the pertinent design parameters of the helix slow-wave structure. Therefore a new trend has been initiated at CEERI to use Ansoft HFSS code to analysis of the helix slow wave structure in its real environment. The analysis of the helix SWS for Ku-band 140W space TWT has been carried out and compared with experimental results, and found is close agreement.     

Slow-Wave Characteristics of a Frame–Rod Structure Based on Micro-Fabricated Technology for THz Vacuum Electron Devices

A simple equivalent circuit analysis of the frame–rod slow-wave structure (SWS) on dielectric substrates of a traveling-wave tube (TWT) is developed, using the quasi-TEM approximation approach for the dispersion and coupling impedance characteristics of the structure. Moreover, the obtained complex dispersion equation and coupling impedance are numerically calculated. The calculation results by our theory method agree well with the results obtained by the 3D EM simulation software HFSS. It is shown that the dispersion of the frame–rod circuit is decreased; the phase velocity is reduced and the bandwidth becomes greater, while the coupling impedance decreases after filling the dielectric materials in the frame–rod SWS. In addition, a comparison of slow-wave characteristics of this structure with a rectangular helix counterpart is made. As a planar slow-wave structure, this structure has potential applications in compact TWTs based on the micro-fabrication technology, which could be scaled to millimeter wave, even to THz frequency.     

Analysis of a U-shaped vane-loaded helical slow-wave structure for wideband travelling-wave tubes

The dispersion equation and interaction impedance of a U-shaped vane-loaded helical slow-wave structure (SWS) is obtained by considering the azimuthal space harmonic in the non-vane region and the helical tape thickness, using the field theory matching method in the azimuthal field discontinuity. The theoretical calculation by electromagnetic analysis is consistent with the simulation result by MAFIA, which can explain some physical essence of the SWS. In the helical SWS, negative dispersion is reported to reduce the second harmonic content of a wideband travelling-wave tube at the low-frequency end of the band. When the SWS is assembled, the support rods are easily located in the groove of the vane. The solution provides a new instruction method for other types of vane-loaded helical SWS.     

Design of Coaxial Couplers for High Efficiency Helix TWT

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.