共查询到20条相似文献,搜索用时 156 毫秒
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利用模式展开与场匹配理论,建立了具有突变结构的开放式波导谐振腔的级联散射矩阵,在此基础上编写Matlab计算程序,通过数值计算,分析了回旋速调管输出腔的腔体长度和半径变化、输出耦合孔的半径和厚度变化、正弦渐变段的长度和起始半径的变化等对输出腔的品质因数和频率的影响,并分析了正弦渐变段的长度和起始半径的变化对反射参数和对杂模的影响。给出了中心频率35.02GHz、Q值为110.1、TE02模带正弦渐变段输出腔的设计参数。同时,在三维高频分析软件HFSS中建立三维模型,进行仿真对比,结果表明:数值计算与三维高频软件仿真结果基本吻合。 相似文献
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为了模拟回旋管输出的TE62模,需要设计一个模式激励器。文中采用同轴波导谐振腔结构,通过选择合适的内外导体半径比及腔体尺寸,来获得纯度较高的TE62模。并使用HFSS 软件对腔体进行了仿真,仿真计算结果与理论值相吻合,表明这种结构是可行的。 相似文献
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在回旋行波管的设计过程中,输出结构性能的高低直接影响到整管增益的高低以及输出功率的大小。采用切比雪夫渐变波导作为耦合输出段,通过对轮廓线的计算程序进行改进,将中心频率作为可变量进行了修正。仿真结果表明,长度为75mm改进后的切比雪夫渐变结构不仅能抑制工作模式向杂模TE02和TE03的耦合,还能有效减少工作模式的反射。在整个工作频段内,杂模TE02和TE03的耦合系数分别低于-33dB和-65dB,TE01模的反射系数低于-20dB,TE01模的传输系数高于-0.01dB。 相似文献
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利用正余弦拟合的方法和半径渐变波导的耦合波理论,设计出一种Ka波段TE01模回旋速调管带该新型渐变段输出腔。通过Matlab数值计算和HFSS仿真优化,研究了该新型渐变段的传输参数、反射参数、对杂模的抑制等性能指标。仿真结果表明:在渐变段长度为80mm、口径由14mm变化到32mm的情况下,在33~35GHz的范围内该新型渐变的传输参数大于-0.016dB,反射参数小于-55dB,对TE02模的耦合为-25dB和对TE03模抑制在-55dB以下;而该输出腔的中心频率为34.075GHz,Q值为109.6,工作模式TE01模式的模式纯度大于0.94。 相似文献
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在耦合波理论的基础上,详细讨论了3mm二次谐波渐变复合腔回旋管内置TE03—TE02—TE01模式转换器,并使模式转换器兼作回旋管的收集极.采用波纹波导结构和不同的相位重匹配技术进行优化分析,得到了可靠的最优几何参量.以此结果设计出了紧凑、高效的94GH z波纹波导模式转换器,并在回旋管的热测实验中测出模式样图. 相似文献
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研究了渐变型空芯波导(GTHW)在太赫兹波段的传输特性。基于几何光学方法,仿真分析了波导的输出光束质量和传输损耗特性。相比均匀型空芯波导,当光从渐变型空芯波导的大端传输至小端或沿相反方向传输时,渐变型波导具有特殊性能。当光从波导大端传输至小端,渐变型和均匀型波导具有相似的弯曲附加损耗,并且渐变型波导具有更高的耦合效率,便于与多种光源耦合;当光从波导小端传输至大端,渐变型波导的传输损耗和输出光束发散角更小。仿真了波导弯曲率、光源发散角和波导锥度等参数对传输损耗的影响。采用波长532 nm的半导体激光器作为光源,进行了验证实验。测量数据与仿真结果有很好的一致性。 相似文献
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Zhou Lezhu Xu Chenghe Gong Zhonglin 《Journal of Infrared, Millimeter and Terahertz Waves》1982,3(1):117-136
Based on the analysis of wave propagation in a waveguide with slowly varying cross-section, a general theory is developed for microwave open resonators with rotational-symmetric waveguides; this geometry has been extensively used in the gyrotrons. The theoretical analysis is carried through under the most general conditions, that is the cross-section radius r(z) of the resonator is a slowly varying arbitrary function of z and the resonator is open. The general expressions for the resonant frequencies and the Q have been derived. A design method for this kind of open resonator has been proposed. Calculation results for two practical resonators are presented. 相似文献
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R. Minami A. Kasugai K. Takahashi N. Kobayashi Y. Mitsunaka K. Sakamoto 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(1):13-24
A high efficiency launcher of quasi-optical (QO) mode converters for high power gyrotrons have been designed and tested. A helical cut launcher radiates the RF power via its straight cut onto the first phase correcting mirror. The launchers have been optimized for the TE31.8 mode at 170 GHz and TE22.6 mode at 110 GHz by numerically optimizing a launcher surface. The helical cut of the launcher has been optimized by taking the taper angle into account. Further more, the amplitude of the surface perturbation have been optimized for improved focusing in order to reduce the diffraction losses at the helical cut. Low power measurement shows a good agreement with the design. High efficiency characteristics of the design have also been calculated on the assumption of frequency downshift due to the thermal expansion of the cavity and stepwise frequency tuning by changing the operating mode. Besides, the possibility of high efficiency launcher for higher mode is discussed, and these results give the prospect to high efficiency long pulse gyrotrons. 相似文献
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In this paper,we have calculated the band structure of strained quantum well (QW) semiconductor optical amplifiers (SOAs) by using plane wave expansion method (PWEM) and finite difference method (FDM),respectively.The difference between these two numerical methods is presented.First,the solution of Schr(o)dinger's equation in a conduction band for parabolic potential well is used to check the validity and accuracy of these two numerical methods.For the PWEM,its stability and computational speed are investigated as a function of the number of plane waves and the period of QW.For FDM,effects of mesh size and QW width on its accuracy and calculation time are discussed.Finally,we find that the computational speed of FDM generally is faster than that of PWEM.However,the PWEM is more efficient than the FDM when wider SOAs are needed to be calculated.Therefore,to obtain high accuracy and efficient numerical solutions for band structures,numerical methods should be selected depending on required accuracy,device structure and further applications. 相似文献
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针对直升机桨叶共锥度测量中背景复杂、圆形标记点较小,易出现定位不准的问题,提出一种新的圆形标记点定位方法.首先,利用OTSU图像分割方法计算阈值;然后,以OTSU阈值为边界阈值,对图像进行多重分割;利用圆度特征和质心变化规律,对每一次分割后的连通域轮廓进行干扰排除,实现圆形标记点的粗定位;最后,采用最小二乘拟合法完成标记点的精确定位.通过圆形标记点定位实验,表明该方法在复杂场景下对较小的圆形标记点具有较高的定位精度,可用于提高大场景复杂环境下直升机桨叶共锥度测量精度. 相似文献
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大功率微波真空电子学技术进展 总被引:8,自引:0,他引:8
本文综述了近十年来微波真空电子技术进展,由于其在现代军事装备中的重要作用和近十年来技术上取得的进步,使微波真空电子器件在未来30年中仍然是国防装备的核心器件.大功率行波管、微波功率模块(MPM)、多注速调管、回旋管和微型真空电子器件等是正在发展中的重要器件;真空电子器件和半导体器件之间的相互结合与渗透,必将建立兼有两者优点的、性能更加优良的新一代大功率微波电子器件. 相似文献
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M. Glyavin S. Sabchevski T. Idehara I. Ogawa S. Mitsudo K. Ohashi H. Kobayashi 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(8):1211-1221
High-harmonic gyro-devices with axis-encircling electron beams known as large orbit gyrotrons (LOG) represent an appealing alternative to the conventional gyrotrons. In this paper we investigate the feasibility of such device operating with low current and low energy electron beams formed by a novel electron gun with a permanent magnet system. The results from the numerical experiments indicate the possibility to excite TE41 mode at fourth harmonic of the cyclotron frequency. Simulations predict generation of microwave radiation with frequency 104 GHz and output power near 1 kW. 相似文献
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Krupnov A.F. Markov V.N. Golugyatnikov G.Y. Leonov I.I. Konoplev Y.N. Parshin V.V. 《Microwave Theory and Techniques》1999,47(3):284-289
A measurement of ultra-low absorption of microwave radiation in dielectrics is reported. Two Fabry-Perot resonators with ⩾600000 quality factors, fully general-purpose interface bus programmable millimeter-wave frequency synthesizer with 10-15-mW continuous wave (CW) power level, 100-Hz frequency resolution from 78 to 118 GHz, and corresponding hardware and software for signal processing were used. The ±500-Hz accuracy of resonance curve width measurements was reached. This high accuracy allowed loss tangent measurement as small as 10-6-10-7 in dielectric samples with a thickness of ~0.5 mm. A convenient method of measurements of almost arbitrary plane parallel samples has been developed and described. Practical applications such as development and control of thin low-loss resonant windows of powerful (~1-MW CW) gyrotrons used in thermonuclear experiments, precise reflection coefficient of metals measurements, as well as other applications are discussed. The existence of such technique up to frequencies exceeding 1 THz makes measurements described at the whole millimeter- and submillimeter-wave bands affordable 相似文献
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A. I. Harris 《Journal of Infrared, Millimeter and Terahertz Waves》1988,9(3):231-247
Submillimeter receivers which operate in the highest frequency atmospheric windows must still be mounted on large infrared and optical telescopes. Finding the optimum submillimeter wave illumination for these large telescopes is simplified by their effectively perfect optical surfaces and long focal lengths, but is complicated by telescope optics which have been optimized for non-tapered beams. In order to determine the effects of changing illumination edge taper, we calculated idealized aperture and beam efficiencies for telescopes which are used for submillimeter astronomical observations. The optimum illumination edge taper for the large infrared telescopes is near 10 dB, somewhat less than for classical radio telescopes, and is not very critical as long as it is between 10 and 13 dB. We also present an accurate method for measuring the sizes of, and deviations from, Gaussian beam pattern distributions by using astronomical sources which have sizes comparable with the beam. 相似文献