0.22THz宽带折叠波导行波管设计与实验

为了获得0.22THz宽带折叠波导行波管,对行波管的慢波结构和输入输出窗结构进行了宽带设计。通过理论分析和电磁仿真计算出合适的参数,使慢波结构在0.22THz工作点附近的色散曲线平坦,耦合阻抗变化小,模拟计算得到的慢波结构3dB带宽大于16GHz;通过对盒型窗结构及匹配段的优化计算,得到的输入输出结构在大于30GHz范围内S11参数小于-25dB。根据该设计进行了两轮制管和实验研究,得到了一支3dB瞬时带宽约8.8GHz,另一支3dB瞬时带宽大于12GHz的0.22THz折叠波导行波管,中心频率的峰值功率大于400mW。     

Ku波段光子晶体加载曲折波导慢波结构

研究了Ku波段光子晶体加载曲折波导慢波结构的色散特性和耦合阻抗。用电磁仿真软件CST MWS进行了仿真, 讨论了慢波结构外光子晶体对慢波通道内电磁波的选择通过性。对具有相同结构尺寸慢波结构的研究结果表明:光子晶体加载慢波结构的色散比传统曲折波导慢波结构的色散低;和传统曲折波导慢波结构相比,光子晶体加载曲折波导慢波结构的耦合阻抗略高。     

曲折圆形槽波导慢波系统的高频特性

 对曲折圆形槽波导新型慢波系统的高频特性进行了研究，通过理论分析和数值计算，得到了它的色散曲线和耦合阻抗表达式，并分析了结构参数变化对色散特性和耦合阻抗的影响。研究表明：当周期变小时色散减弱，耦合阻抗增加；而增大直波导长度时色散变弱，但同时耦合阻抗也会下降。因此较小的周期有利于改善曲折圆形槽波导慢波电路的高频特性。鉴于这种电路的耦合阻抗较低，可以适当地减小直波导长度来提高耦合阻抗。曲折槽波导结合了曲折波导散热能力强、色散特性好、容易加工和槽波导单模工作、低损耗、大尺寸等优点，在毫米波及亚毫米波段的行波管中具有较好的发展前景。     

140 GHz带状注弯折波导SU-8工艺与传输特性(英)

对140 GHz 带状注弯折波导的色散特性和耦合阻抗进行了仿真。CST微波工作室的仿真表明该波导在140 GHz时,波导内电磁波的轴向相速度为0.227c,且140 GHz频率附近色散特性平坦。波导的耦合阻抗在140 GHz时为5 左右。CST粒子工作室注波互作用的仿真结果表明该弯折波导在140 GHz处的功率增益为24.6 dB。该弯折波导带状电子注的设计保证了该波导的加工工艺与MEMS微加工工艺兼容。通过SU-8 UV-LIGA工艺实现了对该波导的微型加工。测试结果表明该波导的反射损耗S11与插入损耗S21分别为-28 dB和-1.2 dB。实测的输出功率增益达到23 dB。测试结果和仿真结果的一致性表明该弯折波导设计的合理性,同时也验证了多步SU-8 UV-LIGA工艺可以实现对该波导的高精度加工。     

140GHz带状注弯折波导SU-8工艺与传输特性（英文）

对140GHz带状注弯折波导的色散特性和耦合阻抗进行了仿真。CST微波工作室的仿真表明该波导在140GHz时,波导内电磁波的轴向相速度为0.227c,且140GHz频率附近色散特性平坦。波导的耦合阻抗在140GHz时为5Ω左右。CST粒子工作室注波互作用的仿真结果表明该弯折波导在140GHz处的功率增益为24.6dB。该弯折波导带状电子注的设计保证了该波导的加工工艺与MEMS微加工工艺兼容。通过SU-8UV-LIGA工艺实现了对该波导的微型加工。测试结果表明该波导的反射损耗S11与插入损耗S21分别为-28dB和-1.2dB。实测的输出功率增益达到23dB。测试结果和仿真结果的一致性表明该弯折波导设计的合理性,同时也验证了多步SU-8UV-LIGA工艺可以实现对该波导的高精度加工。     

同轴任意槽形周期圆波导慢波结构色散特性的研究

用阶梯近似的方法分析任意槽形加载的圆波导慢波系统，利用各阶梯相邻面的导纳匹配条件 以及中心互作用区与加载区的场匹配条件，获得了任意槽形加载周期慢波结构的统一色散方 程. 利用该色散方程，得到色散特性与CST MWS仿真软件模拟结果良好符合. 分别求解几种 特殊槽形加载慢波结构的色散特性及耦合阻抗，其中，三角形结构色散和耦合阻抗均最弱， 而倒梯形结构色散最强，耦合阻抗最大. 关键词： 任意槽形 慢波结构 色散特性 行波管     

0.14THz行波管的设计与实验研究

以折叠波导作为为慢波结构进行研究分析,利用三维电磁仿真软件HFSS和CST,对0.14THz行波管模型进行了折叠波导慢波结构、电子光学系统和输入输出窗等的模拟设计,并完成了整管的PIC注波互作用的仿真计算与优化。进行了整管的焊接工艺设计和热测实验,研制出的样管在电压15.4kV、电流17.4mA下,脉冲工作输出最大功率为8.3 W,输出中心频率为140.8GHz,最大增益为28dB,-3dB带宽为2.9GHz。     

具有任意槽的矩形波导栅慢波结构高频特性的研究

将任意形状槽的连续轮廓近似用一系列相连的矩形阶梯近似，利用各阶梯面上导纳的匹配，以及槽与互作用区边界场的连续与匹配条件，获得了具有任意槽的矩形波导栅慢波结构的色散方程和耦合阻抗的表达式，并进行理论上的验证.加工制作了矩形槽波导栅模型，冷测表明理论值与测量值相吻合.分别求解几种特殊槽形矩形波导栅慢波结构的色散特性及耦合阻抗，其中，三角形结构的色散和耦合阻抗均最弱，而倒梯形结构色散最强，耦合阻抗最大. 关键词： 矩形波导栅 任意槽 色散特性 慢波结构     

V波段大功率带状注曲折波导行波管

利用曲折波导慢波结构和一个长宽比为3∶1的带状电子注作为注-波互作用电路,完成了对V波段大功率行波管互作用电路的设计。分析了带状电子注通道对高频特性的影响,并在综合考虑色散和耦合阻抗的情况下得到了优化的结构参数。建立了3维的V波段带状注曲折波导行波管的电路模型,并利用CST粒子工作室完成了注-波互作用的仿真研究。研究结果表明,当工作电压和电流分别为17 kV和150 mA时,带状注曲折波导行波管在58~62 GHz时的饱和平均输出功率大于160 W,增益大于34.7 dB。     

变周期大结构低压工作折叠波导行波管的理论与模拟研究

为解决工作在3 mm波段及以上频段的折叠波导行波管因加工精度和功率容量的局限性, 提出了非渐变型有限变周期折叠波导慢波结构. 首先给出了这种结构能够有效增大高次空间谐波耦合阻抗的理论基础, 并导出了色散和耦合阻抗表达式; 然后进行数值计算, 给出一组优化后的设计参数, 并以此确定行波管的工作点; 最后利用MAFIA粒子模拟软件进行大信号互作用模拟, 获得有效增益. 在结构和周期都比较大的情况下, 实现了相对工作电压比较低的行波管设计. 关键词： 折叠波导 变周期 高次模式 行波管     

Theoretical Study for Folded Waveguide Traveling Wave Tube

A wideband folded waveguide traveling-wave tube (TWT) amplifier has advantages of simpler coupling structures and robust structure over the conventional helix TWT. The phase velocity of waves in folded waveguide is slowed down to the velocity of electron beam. Slow-wave interaction with the electron beam in folded waveguide is studied in a linear fashion. For a cold beam, the linear theory predicts a gain of 2 dB/cm and a bandwidth of 37% at the center frequency of 14 GHz. A closed algebraic dispersion relation for the frequency and the axial phase shift per period is obtained using an equivalent circuit model. Numerical solution calculated from the dispersion relation and three-dimensional electromagnetic code, HFSS simulations predict a mode coalescing in the folded waveguide. And a theoretical phase velocity prediction of the electromagnetic wave in this circuit is verified by HFSS simulations.     

Design of a re-entrant double-staggered ladder circuit for V-band coupled-cavity traveling-wave tubes

The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, as well as easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling-wave tube is constructed. The electromagnetic characteristics and the beam-wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.     

Design of a reentrant double staggered ladder circuit for V-band coupled-cavity traveling-wave tube

The reentrant double staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, besides the easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling-wave tube is constructed. The electromagnetic characteristics and the beam--wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.     

Investigation of a wideband folded double-ridged waveguide slow-wave system

The folded double-ridged waveguide structure is presented and its properties used for wide-band traveling-wave tube are investigated.Expressions of dispersion characteristics,normalized phase velocity and interaction impedance of this structure are derived and numerically calculated.The calculated results using our theory agree well with those obtained by using the 3D electromagnetic simulation software HFSS.Influences of the ridge-loaded area and broad-wall dimensions on the high frequency characteristics of the novel slow-wave structure are discussed.It is shown that the folded double-ridged waveguide structure has a much wider relative passband than the folded waveguide slow-wave structure and a relative passband of 67% could be obtained,indicating that this structure can operate in broad-band frequency ranges of beam-wave interaction.The small signal gain property is investigated for ensuring the improvement of bandwidth.Meanwhile,with comparable dispersion characteristics,the transverse section dimension of this novel structure is much smaller than that of conventional one,which indicates an available way to reduce the weight of traveling-wave tube.     

345 GHz折叠波导行波管中电磁传输损耗的分析计算

利用电导率等效方法对345GHz折叠波导行波管中的电磁信号的传输损耗进行了仿真研究,考察了流通管孔径、加工粗糙度等对冷腔传输损耗的影响。结果表明,流通管孔径较大或加工粗糙度较大都会导致电磁信号传输严重衰减。模拟分析了热腔中电磁信号衰减对慢波结构净增益、带宽、最佳周期数等器件特征参数的影响,结果显示,电磁信号衰减会使得增益下降和带宽降低。     

Study of the double rectangular waveguide grating slow-wave structure

A slow-wave structure (SWS) with two opposite gratings inside a rectangular waveguide is presented and analysed. As an all-metal slow-wave circuit, this structure is especially suited for use in millimetre-wave travelling wave tubes (TWTs) due to its advantages of large size, high manufacturing precision and good heat dissipation. The first part of this paper concerns the wave properties of this structure in vacuum. The influence of the geometrical dimensions on dispersion characteristics and coupling impedance is investigated. The theoretical results show that this structure has a very strong dispersion and the coupling impedance for the fundamental wave is several tens of ohms, but the coupling impedance for --1 space harmonic wave is much lower than that for the fundamental wave, so the risk of backward wave oscillation is reduced. Besides these, the CST microwave studio is also used to simulate the dispersion property of the SWS. The simulation results from CST and the theoretical results agree well with each other, which supports the theory. In the second part, a small-signal analysis of a double rectangular waveguide grating TWT is presented. The typical small-signal gain per period is about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4\%.     

Linear Analysis of Folded Double-Ridged Waveguide

A novel slow-wave structure (SWS), the folded double-ridged waveguide structure, is presented and its linear gain properties are investigated. The perturbed dispersion equation is derived and the small signal growth rate is calculated for dimensions of the ridge-loaded region and the parameters of the electron beam. The novel structure has potential applications in the production of high power and broad band radiation. For a cold beam, the linear theory predicts a gain of 1.1-1.27dB/period and a 3-dB small-signal gain bandwidth of 30% in W-band. A comparison between the folded double-ridged waveguide SWS and folded waveguide SWS (FWSWS) shows that with the same physical parameters, the novel SWS has an advantage over the FWSWS on the bandwidth and electron efficiency.     

Analysis of a Novel Ka-band Folded Waveguide Amplifier for Traveling-Wave Tubes

A novel Ka-band folded waveguide （FW） amplifier for traveling wave tubes （TWT） is investigated. The dispersion curve and interaction impedance are obtained and compared to the normal FW circuit by numerical simulation. The interaction impedance is higher than a normal circuit through the whole band. We also study the beamwave interaction in this novel circuit, and the nonlinear large-signal performance is analyzed by a 3-D particlein-cell code MAGIC3D. A much higher continuous-wave （CW） output power with a considerably shorter circuit compared to a normal circuit is predicted by our simulation. Moreover, the novel FW even has a broader 3-dB bandwidth. It therefore will be useful in designing a miniature but high-power and broadband millimeter-wave TWT.