基于XFDTD评估雷电对计算机内部电磁环境的影响

用XFDTD软件模拟计算了雷电电场强度为50 k V、上升沿约为4μs、脉宽为20μs的雷电电磁脉冲与计算机耦合后,在计算机机箱内几个典型位置处的耦合电场强度和能量密度随时间变化的曲线,并分析了计算机内部不同位置处的屏蔽效能。耦合产生的能量密度与对计算机系统造成损害的电磁脉冲功率密度的阈值相比可知,机箱内耦合产生的能量不影响计算机的正常工作,但在孔洞处耦合产生的能量很大。     

1 kW微波源机箱电磁耦合的并行FDTD模拟

微波源机箱的不同面板上开有不同数量和大小的矩形孔缝和散热通风孔,电磁脉冲可以通过机箱上的孔缝耦合进入微波源内部,对内部电路和设备造成干扰。通过自动网格剖分技术实现了1 kW微波源的快速建模,采用并行时域有限差分（FDTD）算法模拟了不同极化方向下高斯脉冲正入射1 kW微波源机箱的耦合问题,分析了微波源机箱的电磁脉冲耦合规律。研究结果表明,数值计算结果与电磁软件仿真结果吻合得比较好,电磁脉冲的极化方向对耦合进入微波源箱体内的电场强度影响不大,微波源机箱中心点的谐振特性明显。     

贯通导线对屏蔽机箱内电路HEMP耦合电流的影响

应用时域有限差分法，研究了屏蔽相箱上贯通导线对机箱内电路HEMP耦合电流的影响，研究表明，贯通导线通过与入射场及屏蔽机箱的散射场耦合，可使机箱内与贯通导线直接相连或不相连电路上的HEMP耦合电流显著增强，此研究对电台、微机等电子设备和系统的核电磁脉冲防护具有十分重要的意义。     

核电磁脉冲与开孔金属腔体耦合特性研究

利用基于时域有限差分法(FDTD)的电磁仿真软件XFDTD,研究了核电磁脉冲与开孔腔体的耦合规律。分析了不同极化方向的核电磁脉冲入射时,矩形孔洞长宽比对耦合特性的影响;讨论了核电磁脉冲照射下,腔体谐振和孔缝与腔体的耦合谐振现象;给出了腔体内部电场分布的截面图,讨论了核电磁脉冲入射时腔体内外电场的空间分布情况。研究结果表明:当核电磁脉冲的极化方向与开孔矩形短边平行时,耦合的电场强度比正方形开孔时的要大,且长宽比越大,耦合的电场强度越大;当核电磁脉冲的极化方向与开孔矩形长边平行时,耦合的电场强度比正方形开孔时的小,且长宽比越大,耦合的电场强度越小。极化方向与矩形开孔短边平行时,腔体内产生了腔体谐振和孔缝与腔体的耦合谐振,开孔尺寸的变化会引起谐振频率的偏移;极化方向平行于长边时无明显电磁谐振发生。核电磁脉冲对屏蔽体内的影响主要局限于开孔附近。     

基于FDTD的环形孔缝电磁耦合规律研究

为提高电子设备及系统在复杂电磁环境下工作的稳定性,应用时域有限差分方法对不同脉宽电磁脉冲通过带有不同形状（方形环,圆环,矩形环）环形孔缝屏蔽腔体的耦合规律进行了分析.研究结果表明：电磁脉冲通过环形孔缝耦合现象明显,其通过圆环的耦合能量最小;对于矩形环,当入射波极化方向与环形孔缝的短边平行时,若矩形环孔缝纵横比越大,则耦合能量也越大,当极化方向与短边垂直时,则纵横比越大,耦合能量越小;入射电磁脉冲脉宽越短,电磁脉冲越容易耦合进入环形孔缝;腔体壁的反射及谐振会增强耦合效应.     

线极化波和圆极化波与腔体的耦合比较

线极化波与腔体的耦舍效果受腔体上窄缝方向的影响很大,而圆极化波与腔体的耦合对窄缝方向的依赖比较小。利用时域有限差分法,采用相同振幅的线极化波和圆极化波入射,分别计算它们与开有单缝和T形缝隙的屏蔽腔体的孔缝耦合效应。比较两种极化形式的波入射时,耦合到腔体内部功率密度最大值随极化方向的变化关系,从而得出结论：同幅度的圆极化波比线极化波更容易耦合进入腔体,并不易受缝隙形状影响。     

超宽带双极性脉冲对机箱孔缝的耦合特性研究

为了解超宽带双极性电磁脉冲对于机箱孔缝的干扰与损伤规律,使用基于时域有限积分法的CST电磁仿真软件对机箱建模进行仿真,并分析了脉冲特性及孔缝结构等因素对于脉冲耦合效应的影响.研究表明:双极性脉冲在通过小孔缝耦合进入腔体内部时,脉冲能量主要在孔缝附近,进入腔体后迅速发生衰减,腔体内部的耦合场由腔体谐振模式主导.双极性脉冲...     

非均匀微带线电磁脉冲耦合特性分析

针对电磁脉冲与非均匀微带线的耦合问题,基于时域有限差分法和卷积完全匹配层,研究了不同弯曲和不同斜切角非均匀微带线的电磁脉冲耦合特性,并对耦合机理进行了讨论.仿真结果表明:由于结构的非均匀性,微带线不同端口的耦合系数相差较大;电磁脉冲入射方向对耦合系数具有重要影响,不同方向耦合系数相差约60 dB;微带线拐角斜切对降低电磁耦合效果不明显.所得结论对提高微带电路和电子系统抗强电磁脉冲打击能力具有重要意义     

一种阵列互耦矩阵与波达方向的级联估计方法

当阵列天线存在互耦效应时,传统多重信号分类(MUltiple SIgnal Classification, MUSIC)算法的测向性能急剧下降。为了有效估计阵列互耦矩阵(MCM)与入射信号的波达方向(Direction Of Arrival, DOA),该文提出一种阵列互耦矩阵与波达方向的级联估计方法。利用互耦矩阵的结构特点,变换阵列流形,实现对互耦矩阵与DOA的解耦合。求解线性约束下的二次优化问题,利用谱峰搜索,得到阵列互耦矩阵和入射信号DOA,完成互耦误差自校正。通过计算机仿真验证了该文方法估计性能的有效性和优越性。     

有孔阵箱体电磁脉冲耦合的计算机模拟

日益恶化的电磁环境与越来越苛刻的电路抗干扰工作环境要求，使得电子设备抗干扰能力的研究成为现代及未来电子设备研制，设计与生产急需解决的难题，本文描述了电磁脉冲通过孔阵耦合的数值计算，揭示了一个实际机箱的耦合规律。     

单片机的ESD EMP效应及加固技术研究

ESD EMP(静电放电产生的电磁脉冲)具有上升沿陡、频带宽和峰值大等特点,对电子系统具有很强的干扰和破坏作用。为研究ESD EMP对电子系统的影响,以单片机为实验对象,对单片机系统进行了ESD EMP辐照效应实验。实验表明,单片机系统在ESD EMP作用下,会出现10多种故障现象。文中在实验基础上研究了单片机加固技术。     

Cross polarization losses in periodic arrays of loaded slots

A periodic array of apertures in a conducting plane can act as a bandpass filter. With proper design the structure will be transparent at its resonant frequency but will have a transmission coefficient below unity at all other frequencies. These periodic surfaces are useful as radomes and in dual frequency antenna feeds. The resonant frequency of such an array may vary with incidence angle. This variation is undesirable for most applications, and can be greatly reduced by reactively loading the slots with the Babinet equivalent of a short circuited two-wire transmission line. It has been found, however, that singly loaded slot arrays have transmission loss due to cross polarized radiation when scanned in theH-plane (perpendicular polarization). It is shown that this cross polarized radiation may be eliminated by using symmetrical loaded slots, which have the further advantage of transmitting waves of arbitrary polarization. In conjunction with this investigation, the modal matching method, previously applied to arrays of rectangular and circular slots, has been extended to the more complicated loaded slot shapes. Both the single loaded and 4-legged symmetrically loaded slots are treated, and good agreement with measured data is obtained.     

Shielding Characterization of Metallic Enclosures With Multiple Slots and a Thin-Wire Antenna Loaded: Multiple Oblique EMP Incidences With Arbitrary Polarizations

Shielding effectiveness (SE) of metallic rectangular enclosures with thin slots and a thin-wire antenna loaded by an impedance, illuminated by multiple electromagnetic pulses (EMPs) simultaneously, is investigated using a hybrid finite-difference time-domain (FDTD) method. In order to enhance the simulation efficiency of the FDTD algorithm, accurate formulas for handling multiple thin slots, a thin-wire antenna, and a lumped network are integrated together. Numerical results show that for real metallic enclosures, their shielding performance is very sensitive to the variations in direction and polarization angle of the incident EMPs. However, at a given frequency, the resistance and inductance loaded at the terminal of a thin-wire antenna have little effect on the SE level. For two, three, as well as more EMP incidences, common-frequency interferences will result in strong inner field resonance in the enclosure.      

THE RELATIONSHIP BETWEEN THE EM ENERGY ABSORPTION OF HUMAN BODY AND THE INCIDENT DIRECTION AND POLARIZATION OF PLANE WAVE

The problems of EM energy absorption of human body irradiated by plane wave arediscussed by the Finite-Difference Time-Domain(FD-TD)method.The local Specific AbsorptionRates(SARs),the whole-body average SARs and the layer average SARs for the inhomogeneousblock model of human body with different incident direction and different polarization of theincident waves are calculated.The results show that the appearance of maximum EM energyabsorption is not always at the situation of the front incidence and the local SARs are moreimportant for the interaction of the EM fields with human body.All results provide more infor-mation about the electromagnetic dosimetry for human body.     

The Coupling of Electromagnetic Waves Through Long Slots

The problem of a plane wave incident upon one or more long, parallel slots in an infinite plane screen is treated by the method of moments. A Galerkin's solution with triangular expansion and weighting functions is used. The complete solution for aperture fields, transmission coefficients, near and far fields is formulated and programmed. Arbitrary polarization and arbitrary angles of incidence are treated. Where comparison is possible, there is good agreement with classical results. Wide slots, and multiple slots, which cannot be treated by classical methods, are readily handled by the method of moments procedure. Two separate computer programs have been prepared for a) single slot and b) double slots. The theory is outlined; the computer program is described briefly, and representative examples are given.     

微波脉冲窄缝耦合的数值模拟方法

本文应用一种近似方法，结合时域有限差分法，模拟了微波脉冲与腔体上有限厚度孔缝的线性耦合过程，给出了耦合场对入射波载频、入射场偏振方向、腔体壁电导率以及孔缝尺寸的依赖关系，得出了微波脉冲与孔缝耦合的共振效应和增强效应等规律。     

电磁脉冲对带孔缝腔体的耦合特性

利用时域有限差分方法(FDTD)研究了电磁脉冲对带孔缝导体腔的耦合特性。为减少存储空间而采用非均匀网格法,分别对腔体上开有不同形状(正方形、长方形)和不同数目孔缝时的耦合效应进行分析。结果表明,在孔洞面积相同的情况下,电磁脉冲对正方形孔洞的耦合能量较小;而对长方形,当脉冲的极化方向与孔洞短边平行时,耦合能量最大;此外,把单个孔洞分成总面积不变的多孔洞后,耦合能量减小;同时,在保持通风面积不变的情况下,将原本开在一层屏蔽板上的孔缝交错地开在两层板上,能够明显改善屏蔽效果。     

移动通信基站双极化智能天线扇区功率比*

根据移动通信基站天线广播波束要求,构建了基站双极化智能天线阵的空间三维方向图函数.由此,计算了工作频段内基站天线不同水平面半功率波瓣宽度、不同前后比、不同垂直面电下倾和机械下倾角时,基站天线的扇区功率比和增益.结果表明,基站天线水平面半功率波瓣宽度和前后比是影响扇区功率比的决定因素;基站天线垂直面机械下倾的扇区功率比优于电下倾的扇区功率比.