大功率毫米波环板行波管注波互作用线性理论研究

考虑了电子注的厚度和相对效应，采和场匹配和变分法中的特殊方法－－Ritz-Galerkin法，导出了考虑电子束空间电荷效应的环板行波管的热然散方程，并对该方程进行数值求解，得到了其小讯号增益，讨论了慢波系统几何尺寸和电子注参量对小信号增益的影响，为毫米波环板行波管的设计提供了理论依据。     

脊加载环板行波管高频特性的研究

脊加载环板行波管是一种频带相对较宽的大功率行波管,本文用场匹配和变分原理相结合的方法,研究了脊加载环板慢波结构的导波特性及这种行波管的小信号、大信号特性,讨论了结构的几何尺寸及电子注参量对慢波的传播特性、小信号增益及注-波互作用非线性效应的影响.本文的结果将为脊加载环板行波管的设计提供理论基础.     

电真空器件

001609835GHz 三次谐波低电压回旋管理论研究[刊]/黄勇//电子学报.—2000,28(3).—73～76(C)0016099脊加载环板行波管高频特性的研究[刊]/宫玉彬//电子学报.—2000,28(3).—64～68(C)脊加载环板行波管是一种频带相对较宽的大功率行波管,本文用场匹配和变分原理相结合的方法,研究了脊加载环板慢波结构的导波特性及这种行波管的小信号、大信号特性,讨论了结构的几何尺寸及电子注参量对慢波的传播特性、小信号增益及注-波互作用非线性效应的影响。本文的结果将为脊加载环板行波管的设计提供理论基础。参10     

电子注通道形貌对折叠波导慢波结构的影响

折叠波导结构是一种极具潜力的太赫兹行波管慢波电路.分析了电子注通道形貌对折叠波导高频特性的影响,包括色散特性、耦合阻抗和衰减特性.仿真结果表明,相比于圆形电子注通道,矩形电子注通道的折叠波导结构色散要略微陡一些,损耗也要略微高一些.在中心频率处,矩形电子注通道结构的耦合阻抗比圆形电子注通道结构低0.5Ω左右.皮尔斯小信号理论表明,在中心频率处,矩形电子注通道结构和圆形电子注通道结构的增益速率分别为4.85 dB/cm和5.22 dB/cm,具有相似的3 dB带宽,约为6.3 GHz和7.2 GHz.粒子模拟表明,对于矩形和圆形电子注通道,54 mm(100个周期)的折叠波导慢波结构在220 GHz增益分别为24.42 dB和28.44 dB.     

W波段阶梯型交错双栅慢波结构行波管的研究

为了提高传统交错双栅慢波结构行波管的性能,提出了一种阶梯型交错双栅慢波结构,并基于此新型慢波结构,提出了新型输入输出耦合结构.在此基础上,设计了一只工作在W波段的带状电子注阶梯型交错双栅慢波结构行波管.计算结果显示,阶梯型交错双栅慢波结构行波管的耦合阻抗更高,从而使行波管在更短的互作用电路长度里,实现更高的饱和增益和互作用效率.在90～100GHz频率范围内,阶梯型交错双栅慢波结构的耦合阻抗大于4Ω,高于传统交错双栅慢波结构;W波段带状电子注行波管高频结构的反射系数(S11)小于-15dB;并且行波管的饱和输入功率仅约为0.7W,可以实现最高输出功率约800W,相应的效率大于7.8%,增益大于30.6dB.     

太赫兹交错栅慢波结构高频特性理论研究

基于本征函数法对G波段交错栅慢波结构的高频特性建立了理论模型,考虑空间谐波级数项收敛后,计算得到了色散曲线和耦合阻抗以及损耗参量并采用仿真软件对计算结果进行了验证。对比发现理论模型计算的高频特性与仿真结果吻合较好,色散误差小于0.1%,耦合阻抗误差小于10%,损耗误差小于10%,可信度较高。研究结果表明,该模型对于拥有任意交错距离和上下栅高度的双栅结构具有普适性,在两种极限情况下可分别化为对齐双排矩形栅和矩形波导栅慢波结构。交错栅高频损耗主要发生在注通道区域,槽区底部损耗最小。     

任意槽矩形波导栅行波管注-波互作用线性理论研究

在带状电子束假设下,采用场匹配和导纳匹配的方法,导出了存在电子束的任意槽矩形波导栅行波管的"热"色散方程,对该方程进行数值求解,得到了小信号增益,分别讨论了慢波结构槽形状和电子束参量对小信号增益的影响,为毫米波矩形波导栅行波管的设计提供了理论依据.     

W波段V型曲折矩形槽波导行波管的模拟研究

分析了一种新型慢波线-V型曲折矩形槽波导慢波结构,利用电磁仿真软件CST及HFSS对其高频特性进行了模拟计算,并在此基础上设计了工作在W波段的V型曲折矩形槽波导行波管的互作用结构.利用CST粒子工作室对其注-波互作用特性进行了模拟分析.结果表明:W波段V型曲折矩形槽波导行波管能够有效放大微波信号,且频谱纯净.     

槽区加载介质矩形格栅慢波结构的色散与增益

建立了槽区内加载介质的格栅慢波结构模型.通过Borgnis函数法和场匹配法得到冷态和热态色散方程.并推导了耦合阻抗的表达式.在稀疏电子注的假设下,求得增益近似解的表达式.通过数值方法,求解并分析了加载介质对色散关系、基波耦合阻抗、基波相速和基波增益的影响.并指出分别在槽内加载介质和格栅对侧加载介质对高频特性的不同影响趋势.     

阶梯加载矩形波导栅慢波系统的研究

提出了一种新型的毫米波行波管慢波结构———阶梯加载矩形波导栅慢波系统.考虑槽区内场的高次项,利用各阶梯相邻面的阶跃条件以及互作用区和加载区的场匹配条件,获得了该结构的色散方程,并导出耦合阻抗.讨论了主模在其中的传播情况,并分析了系统结构参数变化对慢波电路高频特性的影响.数值计算表明加载阶梯的尺寸对此结构内波的传播特性有很大影响,可以根据不同的要求来选取具体设计参数.该结果为进一步研究和设计此类行波管高频系统提供了理论基础.     

开放式圆柱光栅周期结构的色散特性分析

研究了一种新的开放式圆柱光栅周期结构,该结构可以作为Smith-Purcell自由电子激光和相对论行波管中的慢波结构.采用近似的场论方法,用一系列相连的矩形阶梯来近似代替光栅上任意槽形的槽的连续轮廓,利用各阶梯面上导纳的匹配,以及槽与互作用区的连续和匹配条件,获得了任意形状槽圆柱光栅周期结构的色散方程,并讨论了系统结构参数变化对系统色散特性的影响.利用软件MAGIC对结构的色散特性进行了二维模拟,与理论计算得到的值符合良好.     

ANALYSIS OF RECTANGULAR WAVEGUIDE GRATING SLOW-WAVE STRUCTURE WITH THE ARBITRARY SHAPED GROOVES

The rectangular waveguide grating slow-wave structure (SWS) with arbitrary shaped grooves is presented and analyzed in this paper. As an all-metal slow-wave circuit, it has properties that can be used in high-power millimeter-wave or sub-millimeter wave traveling wave tube (TWT). The unified dispersion equation and the expression of coupling impedance are obtained in this paper by means of an approximate field-theory analysis, in which the profile of the groove is approximately replaced by a series of steps and the field continuity at the interface of two neighboring steps together with the field matching conditions at the interface between the groove region and the interaction region are employed. A rectangular groove SWS was manufactured and the cold measurement was made. The experimental data are in good agreement with the numerical calculation. The derived transcendental equations are resolved numerically for four classical structures such as rectangular, dovetail, ladder and cosine. Finally, taking the rectangular waveguide grating SWS with rectangular grooves for example, the influences of physical dimensions on dispersion relation and coupling impedance are discussed.     

Surface emitting characteristics of silicon waveguides

This paper concerns the surface emitting characteristics of silicon waveguides in the millimeter-wave frequency band. The waveguides used in the experiment are rectangular slabs of high resistivity silicon (30,000 ohm-cm). A series of periodic perturbations on the waveguide surface provide a radiating antenna. A rectangular grating with a period of Λ=1.8 mm, a height of 0.35 mm, and a duty cycle of 0.46 was sawn into the top surface of a silicon waveguide with a width of 3 mm and a height of 1.41 mm. Experiments were performed to measure the attenuation, dispersion and the radiation characteristics of the waveguides. The test setup was used to monitor the frequency, radiation angle, and the radiated power. Measurements are made over a band of frequencies around the second Bragg frequency. The detector was scanned from 88–95 GHz and changes were observed in the attenuation constant, dispersion relation and the far field radiation pattern. From these results we were able to verify the grating theory.     

Coupling coefficients in gain-coupled DFB lasers: inherent compromise between coupling strength and loss

A theoretical analysis of the gain-coupling coefficient for distributed feedback (DFB) lasers with first-order, rectangular, gain, or loss gratings is presented. For the structure with gain grating, the dependence of the gain-coupling coefficient on the modal gain has been taken into account for the first time. In both structures, an inherent compromise between coupling strength and extra modal loss is found. The results show that significant gain-coupling coefficient values are feasible.<>     

Dispersion and gain investigation of a Cerenkov grating amplifier

The sheet electron beam propagation over a rectangular deep groove grating is investigated and the interaction between surface harmonic waves, which are evanescent above the grating surface, with a dilute sheet electron beam is analyzed. It is assumed that a strong axial magnetic field is applied to constrain the motion of electrons along the waveguide axis. Under these conditions, a complex dispersion equation is derived and analyzed by using Taylor expansion. This expansion results in an analytical formulation for the gain. Using the derived analytical formulation of the gain, the effects of beam thickness, beam-grating gap, and characteristics of grating on gain is investigated.     

A new dielectric grating antenna at millimeter wave frequency

The development of a dielectric grating antenna at K/sub a/ band is presented. The antenna performance is analyzed using perturbation analysis and a numerically based commercial software. The effect of the grating profile and various dimensions on the performance is presented. Based on the analytical results a rectangular profile grating antenna is designed. The antenna is optimized, fabricated and measured. Close agreement between the simulated and measured results is obtained.     

Gain flattened distributed fiber raman amplifiers

An S band and a C band distributed fiber Raman amplifiers (DFRAs) with flattened gain and compensated dispersion have been studied and implemented with 1427 nm and 1455 nm mono-wavelength fiber Raman lasers as the pumped sourcesrespectively. The gain of single-wave pumped S band and C band can reach 10 dB and 15 dB respectively. And a 50 nmgain flattened width was successfully obtained by using a chirp fiber Bragg grating (CFBG) gain flattened filter with gainripple of ±0.6 dB. The C band DFRA has been applied to CDMA wireless communication system successfully.     

光纤光栅中反射带隙附近基态孤子的形成条件

利用理论分析和数值模拟的方法,计算了光纤光栅中反射带隙附近光场满足的色散关系,分析了传输脉冲的相速度、群速度与群速度色散（ＧＶＤ）,在此基础上讨论了光纤光栅中基态孤子形成的条件,并提出实现低功率光纤光栅孤子的一些方案,这对于光纤光栅非线性特性的研究具有一定的参考价值。