W波段低损耗径向功率合成器设计

介绍了一种采用圆波导TE01模式转换实现的W波段低损耗径向功率合成器。设计出了16路圆波导TE01模径向合成器和圆波导TE01模转换器,整体结构简洁紧凑,利于加工制造。对合成器在85～105 GHz的频带内进行了背靠背测试,驻波低于1.35。扣除模式转换器的损耗,单个径向合成器损耗小于0.35 dB,合成效率大于92%。     

一种X波段GW级TE21模耦合器的设计

针对目前高功率微波(HPM)传输与发射系统无法实现自跟踪的问题,引入TE21模耦合器,使HPM系统具备自跟踪能力。由于现有的TE21模耦合器应用到HPM中会面临功率容量的问题,为此设计一种X波段GW级TE21模耦合器,以探索其在HPM系统中的应用。仿真结果表明：设计的TE21模耦合器在9.0~10.0 GHz频率范围内,对TE21模的耦合度大于-0.5 dB,对TE11模的耦合度小于-40 dB,功率容量可达到GW量级。     

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…     

基于电光聚合物材料的光圆偏振调制器的研制

设计并研制了基于电光聚合物光波导的光圆偏振调制器(CPM)。所研制器件的TE TM偏振模式均衡器部分能够实现TE模与TM模间90%的偏振转换效率,这为器件输出光波的偏振分量均衡提供了相当大的调节范围。在均衡了波导中TE模与TM模的基础上,实验表明,器件的TE TM相位差调制器部分实现了很好的光波圆偏振调制输出特性。所测得的输出线偏振光中,45°与-45°斜角方向偏振分量的消光比大于25dB。基于接触式电极化法所获得的电光特性,TE TM偏振模式均衡器部分的偏振转换周期电压约为230V,TE TM相位差调制器部分的调制特性曲线周期约为192V。     

过模弯曲圆波导模式耦合设计

基于耦合波理论,波导轴线采用常规圆弧弯曲和改进的正弦弯曲结构,对TE01—TM11模式变换器进行全面优化分析,计算中考虑了多模、反向波、金属壁所带来的欧姆损耗以及相位重匹配等因素.以正弦弯曲设计的Ka波段TE01—TM11模式变换器的转换效率达到99%,带宽超过32%,并得出常弯曲结构中波导半径、波导曲率、变换器长度和转换效率之间的关系.     

同轴TE11模与矩波导TE10模的耦合计算

首先建立同轴TE11模与圆波导TE11模的等效关系。进而将同轴TE11模与矩波导TE10模的耦合问题转化为其等效圆波导TE11模与矩波导TE10模的耦合问题。实验证明,理论计算与实测结果吻合。     

二维光子带隙结构圆波导特性的分析

利用CST微波工作室软件对二维光子带隙（PBG）结构圆波导的传播特性进行了研究。研究给出了PBG圆波导存在高次缺陷TM模的条件;证实了PBG圆波导不存在缺陷TE模,高次TEmax模有可能由于其场分布主要集中在缺陷区域而非常类似于缺陷TEml模（l〈n）,l与n之间的关系则与PBG圆波导的具体结构有关。并对本文的分析结果和计算方法进行了讨论。     

高功率毫米波模式变换中的相位重匹配

在模式耦合理论的基础上,对过模圆波导TM01-TE1模式变换进行了研究．采用不同的相位重匹配方法和选择相应的结构,对TM01-TE1模式变换器进行了优化分析,得出了圆波导半径、弯曲圆波导曲率和频率以及频带宽度之间的变化规律．以此结果可设计出相应的紧凑、高效、宽带毫米波过模圆波导模式转换器．     

指向耦合器型TE/TM模分离器结构参数优化设计

采用简单的理论模型 ,对折射率呈渐变分布的钛扩散LiNbO3 波导进行结构优化 ,得到模式分离的最佳结构参数 ,用光束传播方法 (BPM法 )设计了有金属覆盖层的指向耦合器型TE/TM模分离器 ,偏振串音分别达到 -2 0 8dB(TE模 )和 - 2 1 3dB(TM模 )。     

一种同轴波导TE01模到圆波导TE02模变换器的数值模拟

该文对一种同轴波导TE01(°)模到圆波导TE02(°)模变换器进行数值模拟研究.通过分析同轴波导与圆波导对接产生的模式转换效果,探讨尖劈模式变换段改善工作模式转换系数和工作频带以及抑制寄生模式的作用.利用Ansoft HFSS对模型进行的数值模拟计算结果表明,这种结构能够实现最大将89.3%输入信号能量转换到TE02(°)模,-3dB带宽约820MHz,带内对主要干扰模式TE01(°)的抑制在10dB以上.     

Optimized overmoded TE01-to-TM11 mode converters for high-power millimeter wave applications at 70 and 140 GHz

Mode coupling in bent, oversized, smooth-wall circular waveguides was studied by means of numerical integration of coupled-mode differential equations in order to optimize high-power TE01-to-TM11 mode transducers at 70 GHz and 140 GHz. Such mode transformers are used in the mode conversion sequence TEOn to TE01 to TM11 to HE11 for generating the almost perfectly linearly polarized Gaussian-like HE11 mode from circular electric TEOn gyrotron modes. This quasi-optical HE11 hybrid mode is in many respects ideal for electron cyclotron resonance heating (ECRH) of magnetically confined plasmas in thermonuclear fusion research and for other technical applications. Curvature and ellipticity coupling as well as ohmic attenuation of 6 coupled modes (TE01, TM11, TE11, TE12, TE21, TM21) are included in the coupling matrices. Integral expressions were used for deriving the coupling coefficients for arbitrary modes in bent, smooth-wall waveguide. Lowest level of unwanted spurious modes together with highest transmission efficiency (shortest arc length) is achieved with sinusoidal curvature distribution instaed of constant curvature. The calculated conversion efficiencies of 98.0% at 70 GHz and 95.2% at 140 GHz (interior waveguide diameter D=27.8 mm for 200 kW transmission lines) are in excellent agreement with the measured values of (97.6±0.4)% and (95±1)%, respectively.     

The design of a mode selective directional coupler for a high power gyroklystron†

The design method of mode selective directional couplers from a transverse electric mode in a circular waveguide to the fundamental mode in a rectangular wave guide is presented in this paper. The design results for a TE₀₁ circular mode coupler intended for use in the output power measurement of a high power gyroklystron are reported; these results indicate that more than 50-80dB directivity and sufficient suppression of unwanted modes can be obtained with a coupler less than 07m in length. The effects of frequency and rectangular wave guide size on coupler parameters are also discussed in this paper     

MILO实验模型的频移问题研究

针对目前磁绝缘线振荡器(MILO)实验研究中测量频率与数值模拟所得结果相差较远的问题，利用适用于冷腔的三维电磁场程序对MILO的冷腔结构进行了细致的数值模拟和理论分析。研究发现：该MILO的主慢波结构工作在近π模状态时，其电磁模武除设计的基模TM01外，还存在高阶非轴对称的TM21模式，实验中很可能是由于某种非对称激励导致该系统工作在高阶非轴对称模式，从而使得测量频率与理论设计不符。     

Mode Coupling And Power Transfer In A Coaxial Sector Waveguide With A Sector Angle Taper

We report a theoretical study of mode coupling and power transfer in a coaxial sector taper. The power transferred from the desired TE /sub 01/ mode into other propagating modes is calculated as a function of taper length and operating frequency. Power transfer via mode coupling involves at least three other modes: TE/sub 21/, TE/sub22/, and TM/sub21/. Power transfer as a function of final sector angle is also shown. At sector angles greater than 180° the taper is highly over-moded. This type of waveguide taper is utilized to feed a wide-band input coupler for gyrotron traveling wave amplifiers.     

The design of serpentine-mode converters for high-power microwaveapplications

In this paper, we report the design methodology and numerical results for two mode converters that are suitable for high-power microwave applications. Both converters are designed to operate at 11.424 GHz and utilize periodic serpentine structures to convert between modes with different azimuthal-mode indexes. The first converts about 98.5% of an incident linearly polarized TE₁₂ mode to the TE ₀₁ mode when oriented as an H-plane bend, but has just 1% mode conversion to all modes when oriented as an E-plane bend. The second device converts a linearly polarized TE₁₁ mode to a TM ₀₁ mode with over 99.99% effectiveness. The performance of both devices with respect to parametric variations is detailed. Experimental measurements of the radiation patterns from the TE₁₂ -to-TE₀₁-mode converter are consistent with the theoretical predictions     

Mode selective directional couplers for overmoded waveguide systems

Two types of directional couplers for transverse electric (TE) modes are described: short and multihole couplers, respectively. They selectively pick one mode out of a mode mixture in an overmoded circular waveguide system. Unwanted modes are either statistically kept at low level or are suppressed by destructive interference in the coupling waveguide. Mode selectivity and directivity in multihole couplers oscillate up and down with an increasing number of holes, finally reaching a minimum of approximately 20 dB, unless there are competing modes with rational fractions of the beat wavelength. A multihole coupler for the TE₀₂ mode (28 GHz, 63.4 mm waveguide diameter, 41 holes) and a length of 1.6 m shows a calculated directivity of 68 dB and suppresses the unwanted modes TE₀₁ with 34 dB (24 dB), TE₂₂ with 37 dB (45 dB), and further modes TE_?m (?<5, m<6) with 17 dB to 34 dB in forward direction (figures in parentheses are for unwanted modes propagating in backward direction). A short directional coupler for the TE₀₁ mode (28 GHz, 63.4 mm waveguide diameter) with 16 holes and a length of 230 mm shows a directivity of 55 to 100 dB between 27.9 and 28.1 GHz, suppressing the TE₀₂ mode with 35 to 80 dB, the TE₀₃ mode with 30 to 65 dB, and the TE₂₂ mode with 30 to 70 dB.     

An Adjustable-Slot-Length UHF Coaxial Coupler with Decade Bandwidth (Correspondence)

A coaxial directional coupler has been developed which allows adjustment of the length of the coupling slot to /spl lambda//4 or 3/spl lambda//4 throughout the frequency range 0.3 to 8.5 GHz. Coupling is flat to within 0.05 dB from 0.3 to 3 GHz (/spl lambda//4 mode) and 0.1 dB from 0.9 to 8.5 GHz (3/spl lambda//4 mode). The coupler has 50-dB coupling, 30- to 40dB directivity and was designed primarily for high power measurement (1 to 1000 W) using a low-power meter on the sidearm. The VSWR for the two modes of operation is 1.02 to 1.05. Five octave bandwidth-type couplers would be required to cover this same frequency range.     

Non-polarization and high-coupling-efficiency coupler using multilevel grating structure

A multilevel grating coupler based on silicon-on-insulator (SOI) material structure is proposed to realize the coupling between waveguide and waveguide or waveguide and fiber. This coupler is compatible with the current fabrication facilities for complementary metal oxide semiconductor (CMOS) technology with vertical coupling. This structure can realize coupling when the beams with transverse electric (TE) polarization and transverse magnetic (TM) polarization are incident at the same time. The influences of the grating coupler parameters including wavelength, the thickness of waveguide layer, the thickness of SiO₂ layer and the number of steps on the TE mode and TM mode coupling efficiencies are discussed. Theory researches and simulation results indicate that the wavelength range is from 1533 nm to 1580 nm when the TE mode and TM mode coupling efficiencies are both more than 40% as the grating period is 0.99 μm. The coupling efficiencies of the incident TE and TM modes are 49.9% and 49.5% at the wavelength of 1565 nm, respectively, and the difference between them is only 0.4%.     

Circular Waveguide with Sinusoidally Perturbed Walls

Uniform second-order asymptotic expansions are obtained for the propagation of TM waves in a perfectly conducting circular waveguide with sinusoidally perturbed walls using the method of multiple scales. The analysis concerns the interaction of two propagating modes satisfying the resonance condition imposed by the periodicity of the waveguide walls. Two cases of resonance are treated as well as the case of decoupled modes. In the first case resonance occurs whenever the difference between the wavenumbers of the two interacting modes is nearly equal to the wall wavenumber, while in the second case the difference is nearly equal to twice the wall wavenumber. The results of the theory are then applied to the design of a mode coupler.     

介质加载圆柱腔的场分析

本文应用严格场匹配法解决了介质加载圆柱腔的本征问题，计算了圆柱腔在纵向部分填充介质后ＴＥ０１ｎ模和ＴＭ０１ｎ模的本征频率和本征场型的变化。特别分析了本征模式在空气段为截止模的情况。本文的分析方法亦可应用到纵向部分填充介质的传输线和其它形状的谐振腔。