电路端口电磁脉冲响应仿真分析

为了将系统辨识理论用于典型电路电磁脉冲效应敏感度预测领域,利用电路仿真软件PSPICE,选用基础单元电路,并在可变的脉冲干扰下获得其端口仿真条件下的响应输出。根据系统辨识理论,运用1组输入输出数据建立电路能量耦合模型。模型的预测输出与实际输出的拟合度能够达到98.5%,说明模型的精度达到了要求。通过改变干扰电压的各项参数,对比实际输出与模型输出的拟合度,检验任意干扰下模型的适用性。结果表明,模型输出的峰值、趋势都能逼近实际输出;参数改变幅度越大,拟合度越低。这一方法能够在一定程度上反映电路对脉冲干扰的敏感性能,为电磁脉冲效应敏感度预测新方法的探索打下基础。     

指挥通信车强电磁脉冲效应仿真分析

强电磁脉冲攻击对指挥通信车系统带来重大安全威胁。针对指挥通信车在高空核电磁脉冲(High Altitude Nuclear Electromagnetic Pulse,HEMP)下的电磁耦合问题,通过数值计算研究车辆结构、线缆和天线的电磁耦合响应,实现指挥通信车电磁脉冲效应的量化分析。仿真结果表明,电磁脉冲通过各种途径耦合到指挥通信车的瞬时脉冲信号足以造成电子设备出现干扰甚至损毁,导致执行任务失败。研究结果为指挥通信车系统的电磁脉冲防护设计奠定了基础。     

电磁脉冲与开孔腔内PCB板级MSL间的耦合研究

因PCB上微带线(MSL)与外界电磁能量耦合而生成感应电流(Current),会对敏感器件造成耦合伤害。而目前对此研究的关注度不够,故以带拐角MSL的PCB板内置于开孔屏蔽腔为研究对象,以Current计算为主要切入点,进行多参数耦合特性计算。先建立相应数值模型并验证建模方法有效性后,外置平面波激励源,利用有限元法考察不同计算位置、有无屏蔽腔、MSL夹角大小及拐角补偿等参数变化对电流的影响。结果表明：直MSL上不同计算位置对Current影响不大,其数值都要比MSL弯折时要大,两者差值随频率增加而逐渐减小;谐振点处腔体抑制效果会被弱化甚至完全失效;MSL与电场E平行放置时,迹线需布成短线,MSL与电场E垂直放置时,迹线可布成长线;MSL宽度增加,电流数值会增加但趋势减缓。拐角补偿方法对提高信号完整性(SI)有效,但对降低电磁耦合作用有限。不会影响谐振点出现位置是上述多参数研究的共性结果。     

电磁脉冲与微带线耦合效应的数值模拟

为了提高电子系统抗强电磁脉冲毁伤能力,采用时域有限差分法与SPICE相结合的混合场路方法,研究了电磁脉冲和微带线的耦合机理.研究表明:由于场结构的复杂性,微带线与电磁脉冲耦合随频率不同表现出不同的耦合方式,一是微带线导体带表面波耦合,极化方向为导体带长边方向;二是微带线导体带与接地板间所形成的缝隙耦合,极化方向为垂直微带线的长边方向.两种耦合方式下传递函数的影响因素截然不同.所得结论对提高电子系统抗强电磁脉冲打击能力具有重要意义.     

强电磁脉冲对相控阵雷达损伤的仿真计算研究

针对雷电电磁脉冲、核电磁脉冲和高功率微波武器电磁脉冲等强电磁脉冲容易对雷达造成损伤的问题,根据脉冲防护要求所建议的雷电脉冲、核电脉冲以及非核电脉冲的参数,仿真水平距离上各种电磁脉冲产生的电磁场强分布和功率谱密度分布,分析天线对各种电磁脉冲的耦合特性,计算屏蔽设备对电磁脉冲的屏蔽效能,综合评估易损伤模块针对各种脉冲的响应特性和损伤效应,对雷达电磁脉冲防护设计有一定的指导意义。     

混合电路的PCB设计

高速PCB的设计中,混合电路干扰问题的解决是比较棘手的,而这部分电路常常又是系统能否正常工作的关键所在。通过深入分析干扰产生的机理,结合作者在实际设计中的体会,提出了混合电路一般处理原则,并通过两个混合电路的处理实例,给出两种电源和地的处理方案,实践证明,这样有效减小了数模混合电路间的耦合互扰,从而获得了较好的系统整体性能。     

含贯通线及PCB板开孔腔体的电磁耦合研究

外界能量通过贯通线进入开孔屏蔽体,与PCB上MSL耦合而生成感应电流(Current),加剧了对敏感器件的耦合伤害。故建立含贯通线及PCB板开孔屏蔽腔模型,进行多角度耦合特性计算。在建模有效性验证后,利用有限元法探讨平面波激励下PCB不同模型、MSL上不同端接电阻、贯通线半径、贯通线与腔体壁相接及多贯通线等参数变化对Current的影响规律。结果表明:双介质模型的使用更接近实际PCB 结构对场的影响;两端接电阻取值相差不大条件下,可不考虑与MSL的阻抗匹配,取值也可不相等;Current 数值随贯通线半径的增加而增加;贯通线与腔体壁不同表面相接对应Current幅值要远高于非接触的情况,并会激出新的谐振点。多根贯通线及线间距改变时Current幅值都要高于单线的情况,尤以第一谐振之前更为明显,多线存在不会影响谐振点出现位置。     

数模混合电路的PCB设计

高速PCB的设计中,数模混合电路的PCB设计中的干扰问题一直是一个难题。尤其模拟电路一般是信号的源头,能否正确接收和转换信号是PCB设计要考虑的重要因素。文章通过分析混合电路干扰产生的机理,结合设计实践,探讨了混合电路一般处理方法,并通过设计实例得到验证。     

基于改进型Elman网络的TVS电磁脉冲效应仿真

针对传输线脉冲(Transmission Line Pulse,TLP)测试方法实施过程工作量较大、实验结果与实测数据吻合较差的问题,提出一种基于改进型Elman神经网络的电磁脉冲(Electromagnetic Pulse,EMP)响应建模方法。在TLP方法基础上增设机器模型静电放电和人体金属模型静电放电2类电磁脉冲,利用隐含层神经元数目为10的改进型Elman神经网络对NUP2105L型瞬态抑制二极管(Transient Voltage Suppressor,TVS)的实验数据进行建模,并预测不同脉冲条件下TVS的响应。仿真结果表明,该方法建模精度高、泛化能力强,能够定量判断TVS性能,满足电路快速选件需要。     

Propagation effects for electromagnetic pulse transmission

We review past research on the propagation of electromagnetic pulse signals over the surface of the earth with emphasis on analytical methods to predict waveforms. The best example is the electromagnetic field radiated from a lightning stroke that can be observed at global distances or very close in if one has sufficient motivation. In any case, the propagation channel will distort the signal wave shape because of the strong frequency dependence of the attenuation factors and the phase velocities of the modes. We begin with a flat earth model that has the virtue of simplicity particularly when displacement currents in the earth are relatively small compared with the conduction currents. Here we see that the rise time of the ideally radiated step function signal is of the order of a few microseconds at a range of 50 km over average land paths. Such a prediction is in accord with published experimental data. At greater ranges, earth curvature comes into play and we show here how various analytical and numerical methods can be used in overlapping time regions which serves as a good consistency check. Other complicated effects such as mixed land-sea paths and ionospheric influences are also reviewed.     

雷电电磁脉冲模拟研究

根据雷电在远场产生的电磁辐射场具有平面波的性质 ,提出了一种由冲击波发生器和平行板横电磁室 (PPTC)组成的简易远场雷电电磁脉冲 (LEMP)模拟装置 ,实现对远场雷电电磁脉冲辐射场的模拟 ,并依照 IEC标准用试验验证了该装置的可行性。在此基础上 ,利用此装置对典型电火工品 (EED)进行了辐射试验。     

Specifics of electromagnetic radiation effects on integrated circuits

Modern regulations [1] stress the necessity of testing integrated circuits (ICs) in order to determine the real level of their resistance to single voltage pulses induced by electromagnetic radiation (EMR). With expansion of the EMR spectral composition, however, direct energy release can occur due to the absorption of the EMR field energy by the IC chip itself. To assess this possibility, the relationship is found between different mechanisms of the EMR-induced energy release for the typical irradiation geometry.     

The effects of simulated electromagnetic pulse on commercialaircraft

The susceptibility of commercial aircraft to the SEMP (simulated electromagnetic pulse) hazard is evaluated on the basis of the US Army's AESOP (Army EMP simulator operations) simulator. The following issues are addressed: the AESOP environment at various altitudes, coupling to cables within commercial aircraft, known transient safe levels for commercial aircraft, and determination of threshold levels. Data from, commercial aircraft indicate that civil aircraft critical systems should not be adversely affected by SEMP levels up to about 15 kV/m. This is based on a limited number of data points, however. There is a much larger military database, and it is found from this that perhaps a factor-of-2 margin should be considered to bring the threshold level down to about 8 kV/m     

Full-wave electromagnetic simulation of millimeter-wave active devices and circuits

This paper discusses the most recent progress in developing effective physics-based models for devices operating at millimeter-wave frequencies. The model is based on coupling dynamic electromagnetic wave solutions with carrier transport models. The potentials of this modeling approach for both device simulation and the global simulation of millimeter-wave circuits are demonstrated. Results comparing the full-wave model developed with conventional electrostatic models are provided through the simulation of different microwave transistors. The ability of the model to detect traveling wave effects, such as phase mismatch between the input and output electrodes of a conventional transistor, and their effects on the device gain are also provided. Results from the simulation of an air-bridged gateMesfet, designed to reduce traveling wave effects in high frequency transistors and solve the problem associated with high gate resistance, are illustrated and discussed. Finally, results showing the ability of this technique to model the nonlinearity and the harmonic distortion are provided through the simulation of an amplifier circuit.     

固态脉冲发射机电磁效应分析与仿真

介绍了大功率固态脉冲发射机内的谐振效应和屏蔽盒对电场的扰动效应，阐述了两种电磁效应的产生机理与仿真方法。文中对这两种电磁效应进行了理论分析，说明了电磁效应对发射机的影响，运用先进的微波仿真软件对两种电磁效应分别进行了仿真，并进行了试验，试验结果与仿真结果基本相符。     

电磁脉冲对电缆耦合问题的理论研究

为克服传输线方程求解电磁脉冲电缆耦合问题的不足,提出了有限差分求解电场积分方程的方法,解决了架空电缆电磁脉冲耦合效应的数值模拟难题;引入了基于细线散射的时域有限差分法,解决了地面铺设电缆电磁脉冲耦合效应的数值模拟难题。利用时域电场积分方程方法研究了长度、线径等电缆参数变化及脉宽、极化方向等馈源参数变化对其电磁脉冲耦合效应的影响。给出了电缆耦合电流的波形特征、沿线分布规律。研究表明:在电磁脉冲作用下,自由放置的电缆,其感应皮电流为衰减振铃波形;电流最大值出现在电缆的中心处;随着电缆长度的增加,电缆上的感应皮电流非线性变大;电缆线径的增加、脉冲宽度的改变对其耦合电流峰值影响较小;电场的极化方向对电缆感应皮电流的影响较大。     

Nonlinear differentiating circuits for pulse shaping

The action of a nonlinear differentiator is described. This circuit exploits the nonlinear capacitance of the varactor diode to produce short-duration pulses. Some applications of this circuit are mentioned.     

高速电路的印制板(PCB) 仿真

简要描述了印制电路板的仿真过程，分析仿真对于设计高质量、高精度PCB的重要意义，并在场景产生器的PCB板上使用仿真工具对关键信号(时钟信号)进行信号完整性和EMC分析，以及并行信号的串绕问题分析，根据仿真结果调整了原有设计，从而达到提高了信号质量的目的。