采用矩形到同轴扇形渐变TE□10→TE☉01模式变换器带宽特性的研究

该文对一种矩形到同轴扇形渐变TE□10→TE☉01模式变换器的带宽特性进行了研究.分析了工作频带内竞争模式对工作模式的影响,探讨了滤模加载对改善模式转换性能的作用.模拟结果表明,滤模加载可以削弱竞争模式对工作模式的影响.加滤模结构后,模式变换器工作在Ku波段时,在模式转换效率大于70%的情况下,带宽可以大于700MHz.     

采用矩形到同轴扇形渐变TE10^□→TE01^⊙模式变换器带宽特性的研究

该文对一种矩形到同轴扇形渐变TE10^□→TE01^⊙模式变换器的带宽特性进行了研究。分析了工作频带内竞争模式对工作模式的影响，探讨了滤模加载对改善模式转换性能的作用。模拟结果表明，滤模加载可以削弱竞争模式对工作模式的影响。加滤模结构后，模式变换器工作在Ku波段时，在模式转换效率大于70％的情况下，带宽可以大于700MHz。     

高次模多注速调管同轴输出腔性能改进的研究

该文针对工作在TM310模的多注速调管同轴输出腔中工作模式的场分布均匀性、外观品质因数及其与邻近模式的频率间隔等问题进行了研究,提出了一种带有短路杆和金属环的多注速调管同轴输出腔结构。分析发现,适当设置短路杆和金属环不仅可以使外观品质因数降低,还可以改善工作模式的场分布;而且设置金属环还可以增大TM310模和邻近模式的频率间隔以实现抑制杂模。利用仿真软件对X波段的同轴输出腔进行了模拟计算,计算结果与理论分析一致。在此基础上加工了冷测模型,测试结果表明TM310模与邻近模式的频率间隔均达到了1.2 GHz以上,外观品质因数从507.4降至193.5,工作模式的场分布也变得均匀。     

O型同轴慢波器件的纵向模式选择研究

利用S参数理论,研究了O型同轴慢波结构中最低工作模式对应各纵模的频率、场分布和Q值,并分析了慢波结构周期数对纵模的数目及各纵模Q值的影响.在此基础上提出在O型同轴慢波器件中使用同轴引出结构,可减少慢波结构周期数,不但使器件结构更为紧凑,还可避免纵模竞争,从而提高器件效率、稳定产生微波频率.最后利用PIC方法对理论分析进行了模拟验证.     

X 波段三轴相对论速调管放大器的分析与设计

研究了三轴相对论速调管放大器（TRKA）的模式泄漏和自激振荡问题,对干扰模式的电场分布进行了分析,得 知干扰模式在谐振腔中为TM21 模,而在同轴漂移管中耦合为TE21 模。针对干扰模式的传输特点采用在同轴漂移管中加 载吸波材料的方式进行抑制,通过三维粒子仿真软件分析了吸波材料的电导率和几何参数对微波吸收的影响,根据仿真 分析结果,对同轴漂移管中加载吸波材料的TRKA 结构进行了三维模拟研究,结果表明吸波材料能够很好抑制TRKA 的 自激振荡,模拟仿真实现TRKA 输出微波功率1.1GW,效率37%,增益42dB。     

毫米波TE62准光模式产生器的研究

介绍了准光激励旋转TE62模式产生器的工作机理。采用准光学系统对腔壁带有小孔的谐振腔激励,在毫米波段实现高斯基模转换到旋转TE62模式的转换。重点对腔壁带有小孔的同轴腔体谐振腔内部场结构进行了分析。研究了同轴比对模式分离的影响以及如何选取,提高模式转换器的效率和模式转换纯度。设计了在频率96.4 GHz附近同轴圆波导旋转TE6 2模式激励器。并对装置采用毫米波近场自动测试系统进行实测,模式纯度达到97%。     

3-节滤波器型π-模双间隙腔加载同轴-矩形波导输出电路研究

该文提出了一种适合于低频段中等功率的宽带速调管的新型3-节滤波器型输出电路-π-模双间隙腔加载同轴-矩形波导输出电路,并对输出电路的性能以及各部分结构对输出腔间隙阻抗的影响规律进行详细研究.研究结果表明,同轴-矩形波导混合型输出电路不仅克服了低频段宽带速调管中输出波导尺寸太大而影响聚焦系统的困难,有利于提高电子注通过率和整管效率,同时还具有很好的输出带宽潜力和良好的高功率承受能力.     

具有正交直流场的边廊模(TEm11)回旋脉塞的研究

本文给出了具有正交直流场的边廊模回旋脉塞的线性和非线性分析。对模型的小信号起振,同轴腔内导体对模式的截止频率和分割度的影响以及外加电压对电子回旋频率,起振束功率和互作用效率的影响作了较详细的研究。计算表明,对m=2,互作用效率可达41%。我们还将其结果与相同条件下圆柱腔情况作了比较。这些分析有益于工程设计。     

无线电设备、电信设备

TN811,TN8142005040705一种新型同轴TEM-圆波导TE11模式变换器/刘庆想,袁成卫(西南交通大学理学院)//强激光与粒子束.―2004,16(11).―1421～1424.提出了一种新型同轴插板式模式变换器,可以实现同轴TEM到圆波导TE11模式的变换。介绍了这种模式变换器的工作原理:即通过在同轴波导中沿轴向插入金属板,将同轴TEM模变换成扇形截面波导TE11模,进而利用不同扇形截面波导中的相移改变电场分布的轴对称性,在同轴波导中形成同轴TE11模,最后将同轴TE11模转换为圆波导TE11模式。基于这一原理设计了一个中心频率为3.8GHz的同轴TEM-圆波导TE…     

X波段同轴腔多注速调管的研究

开展了具有同轴谐振腔互作用电路和双模工作杆控电子枪的X波段同轴腔双模多注速调管的研究工作.结合数值计算和冷测实验,对工作于TM₃₁₀高次模的同轴谐振腔模式分布和特性参数进行研究,获得了可满足多注速调管要求的谐振腔特性阻抗和良好的模式稳定性.采用具有双控制极的新型杆控多注电子枪及电子光学系统,可使多注速调管具有双模的新工作特性,通过数值模拟获得了优化的几何参数和具有良好层流性和波动性的空心多电子注.对采用6个电子注和5个谐振腔的X波段多注速调管进行了注波互作用大信号计算,结果表明当电子注电压为21.5kV,脉冲电流为14.4A时,可在30MHz频带范围内获得的100kW左右的脉冲输出功率,互作用效率大于30%,增益大于36dB.     

Integrated Tunable Cavity Gunn Oscillator for 60-GHz Operation in Image Line Waveguide

The design, construction, and experimental test results of a mechanically tunable Gunn oscillator using a recessed diode metal coaxial cavity coupled to an image line waveguide is described. The oscillator frequency was changed by about 10-percent by varying the bias post length into the coaxial structure. The oscillator is designed so that both the Gunn diode and resonant cavity can be quickly replaced to provide extended frequency coverage and efficiency. This Gunn diode oscillator has provided up to 15-mW CW power at 60 GHz with 10-percent tuning range.     

Spectral Domain Analysis of Coaxial Cavities

Coaxial cavities are used in high power gyrotrons as the beam-wave interaction structure. Much research has been devoted to their mode selective properties. A coaxial cavity lacks a sharp boundary at its open end, so it has some physical features that can only be observed using a spectral model, such as frequency-dependent field profiles and mode overlapping effects. These properties are important since cold tests are usually conducted in the frequency domain. This study applies the incident/reflected wave boundary condition to the wave equation of a weakly irregular coaxial waveguide. The resistivity of the wall is considered in the analysis. Calculations reveal that the fixed-position spectrum yields an uncertain resonant frequency and quality factor. Although the maximum-field spectrum can uniquely determine the properties of the coaxial cavity, the resonant frequency obtained using the maximum-field spectral model is inconsistent with that obtained using the temporal model. The field-energy spectrum explains the low Q nature of the coaxial cavity. Moreover, resonant frequencies evaluated using the field-energy spectrum agree precisely with those evaluated using the temporal model.     

一种采用螺旋耦合环的同轴腔可调滤波器

提出了一种采用螺旋耦合环的小型化连续可调的同轴腔可调滤波器.对比传统的单一窗口耦合结构,加入螺旋耦合环可以显著地减小可调滤波器在整个工作频率范围内的带宽变化.采用螺旋耦合环可使可调滤波器插入损耗指标获得进一步改善,并可利用它对滤波器带宽在一定范围内进行调节.基于这种耦合结构设计了一个3腔可调滤波器,并对其传输特性进行了...     

基于模式匹配的同轴腔耦合分析及其应用

采用半解析的模式匹配方法分析并计算矩形同轴谐振腔之间窗口耦合的耦合系数,结合等效电路计算了存在第三个谐振腔时两同轴谐振腔之间窗口耦合的耦合系数.比较了计算两腔的耦合系数时,采用模式匹配法和有限元法的计算效率.结果表明,达到相同精度时,模式匹配法具有更高的计算速度.根据计算所得耦合系数设计了两个分别具有对称响应和非对称响应的C波段同轴腔滤波器,经调试后,滤波器测试结果与设计的理论响应吻合较好,验证了模式匹配方法计算矩形同轴谐振腔通过窗口耦合的耦合系数的有效性.     

Mode coupling in coaxial waveguides with varying-radius center andouter conductors

The mode conversion process in a coaxial waveguide with varying-radius center and outer conductors is shown to be described by a system of first-order differential equations-the coupled mode equations. The nondiagonal coefficients of this system are called the coupling coefficients. In this paper, we derive the explicit expressions for the coupling coefficients in a varying-radius coaxial waveguide and discuss some of their important features. These coefficients can be used in determining model conversion in a coaxial cavity with slowly varying walls or designing and analyzing coaxial waveguide tapers and mode converters. Some experimental results of the coupling coefficients for the case of azimuthally symmetric modes, TE_0n modes, are also given     

An Insulated Coaxial Probe for EM Local Heating

An insulated miniature coaxial probe with a modified geometry has been developed for EM local heating of a biological (or conducting) medium. This probe is basically a lossy coaxial cavity, and its input impedance, current distribution, and power dissipation pattern can be controlled by the selection of terminal impedances, insulating sheath, and the dimensions of the probe. An approximate theory and an experimental study on the probe are presented.     

Experimental Study of a Slot Antenna Excited by a TE011 Mode Coaxial Cavity

A slot antenna is developed to excite the high harmonic waveguide mode for generating large-area plasmas. This antenna consists of a TE₀₁₁ mode coaxial cavity with the axial slots positioned on equal interval on the inner wall. The waves radiated from those slots can excite the high harmonic mode in the central area. With the azimuthal symmetric wave field of the TE₀₁₁ mode, the number of the slots can be chosen to match the field pattern of the high harmonic mode. In this report, the dispersion relation of the coaxial waveguide, the coupling scheme and the mode competition of the cavity are studied. A method has been successfully developed to suppress the TE₁₂₁ mode which is the most competing mode to the TE₀₁₁ mode.     

THz Coherent Vavilov-Cherenkov Radiation in a Special Three-Mirror Cavity

In the modern science and technology a compact and having enough output power terahertz radiation source working in room temperature have earned great attention. This paper is devoted to utilize electron bunches stimulate Vavilov-Cherenkov Radiation (VCR) in a special three-mirror quasi-optical cavity to generate coherent THz waves. This novel three-mirror quasi-optical resonant cavity has the coaxial field pattern which enables field establish in this cavity effectively. The analytical theory of the radiation exited by a train of electron bunches in the special kind of three-mirror cavity has been carried out and the coherent VCR has been achieved by the computer simulation. All those shows that this method can be used to establish useful THz radiation source by the normal electron gun and the commonly used microwave devices.     

Coaxial feeds for high aperture efficiency and low spillover of paraboloidal reflector antennas

Coaxial feeds produce an approximate sector-shaped pattern, an almost optimum pattern of a feed for high aperture efficiency and low spillover of paraboloid antennas. Such a coaxial feed consists of a central circular waveguide which is surrounded by one or more conductors with circular cross sections. Theoretical and experimental investigations on coaxial feeds excited by H11modes have shown that the first ring yields the highest increase in the aperture efficiency of paraboloid antennas illuminated by them. Measurements performed on paraboloid antennas illuminated by a coaxial feed with only one ring yielded aperture efficiencies of 68 to 75 percent for angular apertures of the paraboloidal reflector of100degto160deg. Circularly symmetric patterns in conjunction with almost linearly polarized aperture fields can be achieved by multimode coaxial feeds. The values for the aperture efficiency, which are calculated for paraboloid antennas illuminated by multimode coaxial feeds, nearly reach the theoretical optimum. The measured values are 68 to 80 percent. In addition, the multimode feeds produce very little cross polarization.     

矩形π-TM310模双间隙腔加载同轴滤波器型宽带输出电路的实验研究

本文详细介绍了矩形π-TM310模双间隙腔同轴滤波器型输出电路的实验研究过程,以及针对一些关键技术难点所采取的改进措施.测试数据显示,矩形π-TM310模双间隙腔与输出同轴线的耦合强度适中,其外观品质因数30左右,在加载同轴线之后各个电子注孔特性阻抗的均匀度仍然较好;矩形π-TM310模双间隙腔同轴滤波器型输出电路的输...