HEMP对有限长电缆的危害及其防护

在电磁脉冲环境下，与电子设备相连的电缆会产生感应电流，对电子系统构成了严重的威胁。本文利用时域有限差分法仿真并分析了高空核爆炸产生的电磁脉冲（HEMP）环境下，地面有限长电缆所耦合的感应电流，并针对电缆上产生的过电流提出有限长电缆的电磁防护措施。     

系统级电磁脉冲模拟源辐照试验方法

对全系统进行了抗电磁脉冲分析,分别阐述了系统各耦合环节辐照试验技术和全系统考核验证试验技术。针对高空核爆产生的高空电磁脉冲对地面电子学系统产生的耦合效应情况,分析在系统内部和外部产生感应电流和感应电压的过程;在不同的屏蔽条件下,全系统不同部分将面临不同的耦合效应,采用不同的实验测试方法。重点分析了高空电磁脉冲对电子学系统的作用,在系统内部和外部产生感应电流和感应电压的过程;阐述了不同模拟试验对应的具体对象,并对不同模拟试验方法进行了介绍。     

同轴电缆电磁脉冲耦合仿真分析

采用CST电磁仿真软件,对在金属平板上方的同轴电缆进行高空核电磁脉冲仿真,研究了不同长度、不同线径、不同入射角度、不同接地方式、单层及多层屏蔽时,同轴电缆内部芯线耦合的感应电流及感应电压。     

2020 IEEE EMC&SIPI虚拟会议——提名文章(四)

Testing of a Module for Electrical SubstationS to Demonstrate HEMP and IEMI Protection and GIC Detection 摘要:为了保证安装在变电站中的模块设计的可行性,该模块可以防止电磁武器的早期高空核爆电磁脉冲(E1 HEMP)和有意电磁干扰(IEMI)等大功率电磁干扰,本文进行了一系列测试并给出了相应测试结果. 关键词:HEMP;IEMI;地磁感应电流;辐射和传导测试 根据MIL-STD-188-125-1和IEC 61000-5-10的原则,需要进行相关试验,以确保设计充分.本文涉及的内容包括: ●评估模块及其门的屏蔽效能; ●确定外部场地电缆上的感应电流; ●评估和选择场地电缆上的电缆屏蔽层; ●测试保护模块的电源滤波器; ●测试截止线以下的光纤电缆和气流波导; ●评估电子设备运行产生的内部磁场; ●完全威胁等级E1HEMP测试的结果.     

高空核爆电磁脉冲E2部分对架空管道的影响

高空核爆电磁脉冲会通过管道的耦合作用,对各种电子设备和系统造成严重的影响和破坏.为了研究高空核爆电磁脉冲对架空管道的影响,首先通过麦克斯韦方程给出了高空核爆电磁脉冲对架空管道的耦合方程,然后应用格林函数法求解微分方程得到管道上感应电流和电压的频域表达式,再应用傅里叶反变换得到电流和电压的时域波形.最后计算了基于IEC标准波形的高空核爆电磁脉冲E₂部分作用下架空管道的感应电流和电压.     

地闪电磁脉冲对近地电缆外导体的耦合研究

采用时域有限差分法计算得出地闪回击电流近场在地面附近的分布,将场值代入离散化后的传输线方程后,计算了近地电缆外导体上的感应电流,分析了大地电参数、导线架高、长度以及与雷击通道距离等因素对感应电流的影响.计算结果显示,距雷击通道200m以内的近场对敏感设备及系统构成的威胁最为严重,应作为地闪电磁脉冲环境预测研究的重点.     

电磁脉冲作用下近地电缆外皮感应电流的全波分析

本文采用时域有限差分法,分析电磁脉冲作用下,地面随近同轴电缆所感应的外皮电流。在计算外皮感应电流时,既考虑了传输线模式电流,也考虑了天线电流。该方法适合分析各种电缆的外皮感应电流,所得结果与有关资料作了对比,说明本文的计算结果是合理的。     

海安县有线电视网络的安全接地措施

海安县地处黄海之滨 ,每年进入夏季后 ,雷击次数频繁 ,对有线电视网络造成危害和损失。 2 0 0 0年 6月的雷雨天气 ,给曲塘镇区的有线电视线路造成了很大损失 ,击坏放大器近 30台。其主要原因之一是由于镇区的线路大面积调整后 ,未能及时将“干放”、集中供电等线路器材及钢绞线、电缆屏蔽层采取可靠接地措施。雷电发生时 ,在放电处附近的电缆屏蔽层上形成很强的感应电流 ,由于感应电流不能及时泄入大地 ,就会对有线电视器材造成“反击穿”。针对这种情况 ,我们很快采取了措施 ,具体的做法是 :在放大器所在的电杆下面 ,用 2ｍ长 5 0ｃｍ× 5 …     

架空任意弯曲电缆终端感应电流的计算

该文给出了架设在地面上的任意弯曲电缆在任意极化平面波照射下,其终端感应电流的通用表达式.该表达式考虑到了大地和电缆弯曲形式对电缆终端感应电流的重要影响.该方法对于电子系统的防护以及电磁兼容分析具有一定指导意义.     

大电流作用下电缆转移阻抗非线性特性研究

为了研究屏蔽电缆受外界电磁脉冲作用可能产生的非线性效应,提出了屏蔽电缆表面转移阻抗的大电流注入测试方法.建立了大电流注入测试系统,通过注入测试方法获得了不同电流等级下电缆转移阻抗曲线,对比了两类屏蔽多芯电缆的芯线电磁脉冲耦合情况.实验表明:加入一层铁磁性屏蔽层的多芯电缆在注入电流峰值超过2kA时,芯线耦合电压会呈现非线性效应.并分析了该现象产生的原因.     

Pulse-receiving characteristics of resistively loaded dipoleantennas

The pulse-receiving characteristics of resistively loaded dipoles are analyzed using a time-domain numerical technique. The Wu-King nonreflecting dipole and several other dipoles with higher and lower distributed resistances are considered. The time-domain responses of these dipoles to Gaussian electromagnetic pulses (incident in boresite direction) are calculated. Frequency-domain receiving transfer functions are obtained using the fast Fourier transform (FFT) technique. Dipoles terminated with high resistance loads are also considered. The effect of the distributed resistance and terminal resistance on the pulse response and bandwidth is discussed     

电磁响应的时、频域同时外推法

将散射体在高斯脉冲平面波激励下感应电流的时域响应展开为连带Hermite级数的叠加，利用傅立叶变换和连带Hermite函数的自反性，得到与时域响应形式类似的感应电流的频域响应。根据时域解与频域解的对应关系，利用感应电流的早时响应和低频响应，可确定展开式的未知系数，从而同时获得了时域和频域和完全响应。     

低温生长砷化镓光电导天线产生太赫兹波的辐射特性

研究了低温生长砷化镓光电导天线(LT-GaAs PCA)产生太赫兹(THz)波的辐射特性。利用太赫兹时域光谱(TDS)技术测量了光电导发射极在飞秒激光作用下辐射的太赫兹脉冲,得到了时域发射光谱,并通过快速傅里叶变换(FFT)得到相应的频域光谱。结果表明,低温砷化镓光电导天线产生的太赫兹波信号比飞秒激光激发半导体表面产生的太赫兹波信号具有更高的强度和信噪比;太赫兹波信号与光电导天线的偏置电压成线性关系;随着抽运激光功率的增强,太赫兹波信号增大并出现饱和。     

The Sinc and Cosinc Transform

A new transform, the sinc and cosinc transform, uses Walsh functions to obtain the Fourier transform. This technique converts a staircase approximation of a function to a set of sinc and cosinc terms in the frequency domain that is equivalent to the Fourier transform. The calculation is slower than the fast Fourier transform (FFT) but is devoid of aliasing. The interpolation and scaling in the frequency domain are built in, and any frequency point may be chosen without changing the number or spacing of the samples in the time domain. The intervening set of coefficients is computed more rapidly than those obtained using the fast Hadamard transform.     

Transient scattering by resistive cylinders

The two-dimensional scattering of an electromagnetic pulse normally incident on a collection of infinitely long cylinders of arbitrary shape is considered. ForE-polarization an electric field integral equation is derived that is applicable to solid cylinders and/or thin sheets, resistive and/or perfectly conducting. The contribution of the self-cell at later times is carefully analyzed. The expression obtained represents a generalization of previously known results. For an incident Gaussian pulse, numerical results are presented for surface currents and far-fields, for perfectly conducting and resistive circular cylinders and strips. A fast Fourier transform (FFT) algorithm is implemented to obtain the backscattering radar cross section, which is in good agreement with results obtained from either exact continuous wave (CW) solutions or the method of moments.     

外加电场和磁场对太赫兹辐射产生的影响

通过对半导体太赫兹发射极在有和没有外加电场和磁场作用下发射光谱的测量。说明了外加电场和磁场对太赫兹电磁辐射的产生具有增强作用。采用反射式发射极在飞秒激光作用下辐射太赫兹脉冲的装置，同时利用电光取样方法探测太赫兹电场，得到了这些发射极的时域发射光谱，并通过快速傅里叶变换(FFT)得到了相应的频域光谱。实验表明，太赫兹时域发射光谱和频谱在外加电场、磁场作用下都有增强，但是所发射的频率成分和带宽都没有改变。借助于经典电磁理论的定性分析，认为太赫兹发射光谱在外加电场、磁场作用下的增强起源于半导体中载流子的加速运动受外加电场和磁场的影响。     

Time-domain fields exterior to a two-dimensional FDTD space

A transformation algorithm for the near-zone and far-zone fields exterior to a two-dimensional (2-D) finite-difference time-domain (FDTD) field lattice has been developed entirely in the time domain. The fields are found from a surface integration of the convolution of the time derivative of equivalent currents and charges along a contour that encloses the scatterer or radiator of interest. The kernel of the convolution integral has a square-root singularity for which an efficient numerical integration rule is presented. Using this technique, a very accurate solution is obtained; however, convolution integrals are computationally expensive with or without singularities. As an alternative, a rapidly convergent approximate series expansion for the convolution integral is presented, which can be used both in the near and far zone. Results using the new 2-D transform are compared with analytical expressions for the fields generated by a modulated Gaussian pulse for TE and TM line sources. In addition, the 2-D transform solution for the near-zone fields scattered from an open-ended cavity for a TE incident modulated Gaussian pulse plane wave is compared against a full-grid FDTD solution for accuracy and efficiency. The 2-D transform far-zone fields are compared against an alternative technique, which uses a double Fourier transform to perform the convolution in the frequency domain     

A stable solution of time domain electric field Integral equation for thin-wire antennas using the Laguerre polynomials

In this paper, a numerical method to obtain an unconditionally stable solution of the time domain electric field integral equation for arbitrary conducting thin wires is presented. The time-domain electric field integral equation (TD-EFIE) technique has been employed to analyze electromagnetic scattering and radiation problems from thin wire structures. However, the most popular method to solve the TD-EFIE is typically the marching-on in time (MOT) method, which sometimes may suffer from its late-time instability. Instead, we solve the time-domain integral equation by expressing the transient behaviors in terms of weighted Laguerre polynomials. By using these orthonormal basis functions for the temporal variation, the time derivatives can be handled analytically and stable results can be obtained even for late-time. Furthermore, the excitation source in most scattering and radiation analysis of electromagnetic systems is typically done using a Gaussian shaped pulse. In this paper, both a Gaussian pulse and other waveshapes like a rectangular pulse or a ramp like function have been used as excitations for the scattering and radiation of thin-wire antennas with and without junctions. The time-domain results are compared with the inverse discrete Fourier transform (IDFT) of a frequency domain analysis.     

基于Hemite外推的多柱体时频域电磁散射计算

首先根据散射体在高斯脉冲平面波激励下感应电流的能量几乎全部集中在时间轴和频率轴上的有限范围内,该文将时域响应展开为系数待定的连带Hermite级数的叠加,并根据连带Hermite函数的傅里叶变换的自反性,得到与时域响应形式类似的频域响应;然后利用时域方法和频域方法分别计算散射体上感应电流的早时响应和低频信息;最后经过时域和频域联合外推计算,由早时响应和低频信息确定时域和频域响应的待定系数,从而获得了整个时域和频域的完全响应。该文用这种外推方法分析计算了多导体柱的电磁散射。