Shunt Impedance of Klystron Cavities

Values of R/Qf or re-entrant resonators are given for configurations for which neither the coaxial-field nor the radial-field approximations are valid. The values are calculated by net point methods, and agree well with experimental values obtained by perturbation methods. Some errors arising from the finite dimensions of perturbing plungers are also discussed.     

一种通用的谐振腔简化模型及其分析

本文对一种新的特性阻抗定义作出了合理的的,使其具有更广的适用范围,以波导加载谐振腔为例,采用广义散射参数方法,得到了波导感性膜片不连续性的等效基模散射参数,给出了简洁的等效电路,进而采用传输线谐振理论,分析了几个典型波导谐振腔的工作特性。本文所得结果与已发表的结果吻合良好,证明了本方法的合理性与有效性,此分析方法简明,并且具有清晰的物理意义。     

Resonant Cavities for Frequency Tunable Gyrotrons

In this paper we present, discuss and compare several concepts based on both well-known and novel ideas for tunable gyrotron cavities. Although theoretical and design considerations are presented and discussed together the main focus is on the underlying principles and feasibility of different approaches rather than on their specific implementations. Illustrative examples are provided for configurations and frequency range appropriate for gyrotrons used as radiation sources for NMR spectroscopy with signal enhancement through DNP.     

双腔速调管的三维结构设计与粒子模拟

利用三维PIC软件,建立与双腔速调管几何尺寸完全一致的计算模型,对矩形波导输入和矩形波导输出速调管做了设计和优化,在工作电压80 kV,束流45 A,工作中心频率为2.85 GHz条件下,得到了1.23 MW的输出功率,效率达到了35%,饱和增益达到了20.8 dB.     

Aperture Coupling Between Microstrip and Resonant Cavities

This paper presents a simple analysis for the coupling between microstrip and a cavity through an aperture located in the substrate ground plane. The analysis is based on Wheeler's equivalent-energy concept for small-hole coupling and an approximate parallel-plate waveguide model for the microstrip. The theory appears adequate for most design purposes, and has been used successfully in the design of stabilizing cavities for experimental 12-GHz low-noise FET oscillators.     

Optimization-Based Analysis of Modulation Instability in Resonant Cavities

We present an optimization-based method for the analysis of modulation instability effects in a resonant cavity. This method allows for varying levels of approximation in the solution and for the inclusion of effects such as loss or gain, if significant. The method is then demonstrated with examples showing the effects of the cavity modes on the gain curves.     

Resonant Cavities Used as Frequency Selective Phase Shifters

An application of resonant cavities as frequency selective phase shifters in a multicoupler configuration is described.     

Theoretical Analysis of Resonant Cavities Loaded with Lossy Material

Theoretical analysis of abrupt cavities loaded with lossy material has been described in detail. Dispersion equation for waveguides with lossy material and hybrid modes (HEM) matching equations for abrupt structure were derived. Further, the equations have been solved by numerical calculation to study waveguides and abrupt cavities loaded with lossy material. The theoretical analysis is available for designing and analysis RF devices. It was used to design the RF system for Ka band gyroklystron amplifier, the calculation results accord with the cold test.     

Design of Open-Ended Microwave Resonant Cavities (Correspondence)

This paper summarizes a Ph.D. dissertation on the design and analysis of open-ended microwave cavities. The study was motivated by the need for a cavity with a high measure of quality, Q, through which an unobstructed flow of gases or particulate matter could be obtained. Used in collection with the Crain refractometer, instantaneous measurements of the refractive index of the material in the cavity can be made. Measurements utilizing his technique but with other types of cavities have previously been made in order to study the dielectric properties of smoke and other aerosols.     

Resonant Frequency Calculations for Microstrip Cavities (Correspondence)

Microstrip circuits in metal enclosures frequently exhibit loss spikes. These spikes are sometimes shown to be related to cavity resonances whose frequency can be calculated from enclosure dimensions using known theory. These calculations are presented graphically so that resonant frequencies may be determined for a particular structure or resonances within a band avoided through judicious choice of enclosure dimensions. Comparison of experimental and calculated results are tabulated.     

Cavities Involving Metamaterials With an Uncountable Set of Resonant Frequencies

In this letter, it is shown that cavity resonators involving lossless and nondispersive (in a frequency band) double negative metamaterials can behave in a completely different way with respect to the cavities involving only traditional nondispersive double positive media. More precisely, it is proven that resonators with only nondispersive media may have an uncountable set of resonant frequencies. As practical consequences, it is outlined that this fact can represent an unsurmountable difficulty for present-day numerical simulators of electromagnetic eigenproblems and a cause of troubles for numerical solvers of electromagnetic driven problems. The presented result should warn users of numerical simulators against the employment of simplified models of metamaterials.     

多注速调管外加载谐振腔的分析和模拟

该文对多注速调管谐振腔内加载技术和外加载技术以及相关的微波吸收材料作了分析和比较;理论上阐明外加载谐振腔品质因数的调节途径,用MWS设计出符合要求的外加载谐振腔;对由此产生的模式不对称性进行校正,找出了外加载谐振腔品质因数的影响因素和规律。     

双金属谐振腔温补方法研究

采用双金属的方法对波导温漂进行了补偿,经过推导,在CSTMICROWAVESTUDIO中分别建立了温度变化大于零和小于零的温补模型。仿真结果与理论推导具有很好的一致性,取得了比较好的温补效果。     

高效率激光晶体倍频中晶体谐振腔参数的研究

本文研究了晶体谐振腔的参数如晶体吸收,晶体长度,两端反射率,端面曲率半径,以及激光束半径等对倍频效率的影响,在理论上给出获得高效率倍频输出的途径。     

W 波段回旋管谐振腔特性参数测量方法的研究*

W 波段回旋振荡管是一种重要的高功率毫米波源,它通常采用圆柱开放式谐振腔作为其高频结构。 谐振腔所具有的特性参数,如谐振频率和品质因数影响了整管的性能。在W 波段,特性参数对于尺寸的变化特别敏 感,因此,有必要对加工好的开放式谐振腔的特性参数进行测量。利用直接耦合法实现了对5 组开放式谐振腔谐振 频率和品质因数的无损检测,实验结果验证了该方法的可行性与有效性。同时,分析了加工误差对谐振腔性能造成 的影响,结果表明,当开放式谐振腔渐变角度的加工误差达到7%以上时,谐振频率将偏移0.2GHz。     

Coupling Holes Between Resonant Cavities or Wave-Guides Evaluated in Terms of Volume Ratios

A hole in a common wall is used to provide coupling between two resonant cavities (k=coefficient of coupling) or between two waveguides (x or b=normalized reactance or susceptance) or between cavity and waveguide (p=loading power factor of cavity). Referring to either side of a thin common wall, the field intensity in the center of a small hole is 1/2 what it would have been at that location on the wall. Between two equal regions, the coupling (k, x or b) by magnetic or electric field is expressed as 1/4 the ratio of the effective volume of the hole over the effective volume of each region, by duality (Booker's principle), the effective volume (related to the polarizability) of an aperture in a thin wall is identified with that of an analogous thin body in a uniform field. For a resonant cavity loaded by coupling to a waveguide, the loading power factor is p=kx; this theorem is proved by reference to an equivalent network. Various cases of coupling by two-dimensional and three-dimensional fields are formulated in terms of area or volume ratios, especially between pillbox resonators (rectangular, circular, or coaxial-circular) and between rectangular waveguides with common side walls or top and bottom walls. The effective area or volume of a small hole in a thin conducting wall is given for various symmetrical shapes, in a magnetic or electric field.     

Design and Optimization of TE011 Resonant Modes in Metallic-Dielectric Cavities

In this work, we present an innovative approach for designing small-scale microcavity resonators. By introducing a gold cladding around the structure, we may significantly reduce the mode volume and simultaneously increase the cavity's quality Q-factor. By making use of the TE₀₁₁ mode, as opposed to the more traditional HE₁₁₁ mode, we may further reduce the mode volume while taking advantage of decreased loss into the metal layer due to the optimal polarization choice. We demonstrate a means to design and optimize the cavity geometry to obtain desired spectral characteristics through the use of particle swarm optimization, and we present a cavity operating at 1.5 mum with a Q value exceeding 300 000 and a modal volume of less than 0.9(lambda/n)³.     

高阶矢量基函数在腔体本征值问题中的应用

基于四面体有限单元,采用高阶叠层矢量基函数分析腔体本征值问题,通过若干数值算例验证了在相同计算精度指标下,采用高阶基可以使用尺寸更大的网格,降低未知量个数,提高计算效率;并且通过加密网格,高阶基能够更快地收敛到真解。     

Comments on "Aperture Coupling Between Microstrip and Resonant Cavities" (Letters)

In the above paper, the authors have considered the case of coupling between two identical microstrips in Section II-B. The equivalent model of parallel plate waveguide with magnetic side walls (Fig. 3) has been used for the determination of normalized reactance of a small aperture. The notations and relations of [1] have been used directly for analyzing this equivalent model. It may be noted, however, that the case considered in [1] is of transmission through a transverse plane while the case considered by the authors of the above paper is transmission through broad wall of the guide Fig. 2(b). Therefore, the end result obtained in Section II-B is not convincing.     

A General Power Loss Method for Attenuation of Cavities and Waveguides

The usual power loss method of evaluating the damping constant and Q of cavities and the attenuation constant of waveguides, as caused by finite wall conductivity, breaks down in the case of degenerate modes and fails to predict the coupling between degenerate modes. By means of variational formulations for the lossy case it is shown how the usual power loss method maybe generalized to treat the case when there are degenerate modes present. The generalized method turns out to be a particularly simple extension of the usual procedure.