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针对带孔缝矩形金属腔体在电磁辐射下的屏蔽效能问题,利用基于时域有限积分法的电磁仿真软件CST,建立了平面波辐照条件下含孔缝金属腔体的耦合模型,重点研究了电场极化方向,腔体材料,矩形孔缝的长度、宽度和深度,孔缝填充介质介电常数及其厚度等参数对屏蔽效能的影响规律.研究结果表明:典型金属材料对屏蔽效能的影响差别不大,垂直于电场极化方向的孔缝边长更能影响腔体的屏蔽效能,孔缝尺寸会影响矩形金属腔体的谐振点,孔缝深度能够通过衰减入射波在一定程度上影响屏蔽效能,孔缝填充介质会降低屏蔽效能,介质厚度及其介电常数会影响屏蔽效能峰值点.研究结果对金属腔体的电磁兼容设计有一定的指导意义. 相似文献
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出于通风散热、线缆进出的考虑,弹上很多设备的壳体表面都有孔洞,严重降低了壳体的电磁屏蔽效能,是造成
电磁干扰的重要原因。弹上空间有限,负重对飞行成本的提高很大,且导弹飞行过程中过载很大,因此采取提高含孔缝壳体屏
蔽效能的措施需同时考虑到所占空间、增加的重量和对设备结构强度的影响三个要素。提出了一种提高含孔缝腔体电磁屏蔽
效能的新方法——加装屏蔽立柱,这种方法结构简单,基本不占用屏蔽壳体内的有限空间,也不会明显增加飞行重量,而且不
影响线缆进出、通风散热、结构强度和电气连续性。理论计算和实验测试结果都验证了理论的正确性。 相似文献
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提出一种针对复杂干扰下斜开孔金属腔体屏蔽效能的计算模型。该模型可快速精准地计算出任意金属材料腔体,任意开孔位置,任意观测点位置,任意入射、极化平面波照射以及斜开孔阵腔体的屏蔽效能。首先依据磁流原理和镜像原理将斜开孔腔体等效为两个水平开孔腔体,然后基于Robinson的等效电路法分别求解各自的屏蔽效能,再利用公式换算求得斜开孔金属腔体的屏蔽效能。随后针对腔体会面临的不同干扰,给出不同情况下屏蔽效能的计算方法。考虑多种干扰叠加的复杂工况,将该模型利用Matlab 进行编程,并将计算结果同全波仿真软件CST中的时域传输线矩阵法和频域有限元法的仿真结果进行对比,验证了所提模型的可行性。该模型在保证计算精度的同时,在计算效率上表现出极大的优势。 相似文献
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利用屏蔽室壁面的标准测试窗口测量孔缝泄漏及材料的屏蔽效能 总被引:6,自引:0,他引:6
本文依据标准的屏蔽室屏蔽效能测试原理,测试电磁兼容性结构设计中常见的屏蔽材料性能、缝隙开孔对屏蔽效能的影响.由此得到量化的数据,为屏蔽材料的选型提供技术依据,为工程技术人员进行产品设计提供设计参考.本方法参照了MIL-G-83528,IEEE Std 299-1997等标准推荐的方法和测试程序. 相似文献
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《Electromagnetic Compatibility, IEEE Transactions on》2007,49(2):354-360
The hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) scheme for a 2-D transverse electric (TE) wave is extended to a full 3-D electromagnetic wave in this paper. With the weakly conditional stability, this approach simulates shielding effectiveness of an enclosure with high computation efficiency. Numerical formulations of the 3-D HIE-FDTD scheme are presented, and simulation results are compared to those obtained by using the conventional 3-D FDTD and alternating-direction implicit (ADI) FDTD methods. The accuracy and efficiency of the 3-D HIE-FDTD for prediction of shielding effectiveness are validated by numerical simulation results. 相似文献
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Electromagnetic Fields at the Top of a Tall Building Associated With Nearby Lightning Return Strokes 总被引:2,自引:0,他引:2
We have calculated, using the finite-difference time-domain (FDTD) method for solving Maxwell's equations, the vertical electric field Ez and azimuthal magnetic field Hphi due to lightning return strokes in the presence and in the absence of a building at the field point. Strikes to both flat ground and tall objects of height h = 100, 200, or 500 m are considered. The magnitude of Hphi is not much influenced by the presence of either building at the field point or strike object, while the magnitude of Ez is significantly influenced by either of them. In the case of a lightning strike to flat ground, the magnitude of Ez at the top of the building (at the center point of its flat roof) of plan area Sb = 40 times 40 m2 and height hb = 20, 50, or 100 m located at horizontal distance ranging from 100 to 500 m from the lightning channel is about 1.5, 2, or 3 times, respectively, greater than that at the same horizontal distance on the ground surface in the absence of the building. The enhancement factor for lightning (transient) Ez due to the presence of the building at the field point is essentially not influenced by the presence of the strike object (up to 500 m in height) and is similar to the static electric field enhancement factor due to the presence of the same building in a uniform vertical electric field. The magnitude of the electric field at the corner of the building is about two to three times larger than that at the center point of its flat roof. The magnitude of Ez at the ground level in the immediate vicinity of the building is reduced relative to the case of no building, with this shielding effect becoming negligible at horizontal distances from the building exceeding twice the height of the building. 相似文献
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《Electromagnetic Compatibility, IEEE Transactions on》2009,51(2):170-180
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An approximate formula is derived for the currents in the loads terminating a two-wire line located parallel to and near a circular conducting cylinder of finite length. The line and the cylinder are illuminated by an incident plane wave. The analysis takes account of the coupling between the line and the cylinder and hence of the effects of possible axial resonances in the latter. The configuration simulates exposed conductors used to interconnect the electronic apparatus in a rocket. The analysis is directed toward determining possible hazards due to induced currents. 相似文献
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The location and level of the sidelobes of a radial waveguide pin-fed array antenna, which stem from periodic amplitude and phase errors in the actual antenna aperture field, are derived based on a simple model of a line source as well as the pertinent model of a circular aperture. The theoretical results are verified by comparisons with numerical and measured data 相似文献
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《Antennas and Propagation, IEEE Transactions on》2009,57(1):2-8
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焦重庆 《电气电子教学学报》2014,(5):45-46
本文以导体屏蔽壳、壳外导体、壳内导体及参考导体(大地)构成的4导体静电独立系统为例,详细分析了其电位系数、感应系数及部分电容的取值特性。结果表明,无论屏蔽壳体是否接地,壳外导体与壳内导体的互有部分电容均为零;屏蔽壳体不接地时,内外导体之间存在电场耦合;屏蔽壳体接地后,内外导体之间不存在电场耦合。 相似文献
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金属腔体内的场线耦合是电磁兼容领域的一个重要的问题,基于模式匹配及BLT方程理论,该文提出一种计算带孔阵腔体内场线耦合的方法。将外部激励源对腔体内传输线的耦合分解为孔腔耦合和场线耦合两个过程,腔体内任意点的场强由模式匹配理论及矩量法计算得到,腔体内的场线耦合由Agrawal模型构建BLT方程进行计算。与测试数据对比得出,模式匹配理论可以准确计算腔体内部电磁场。与CST数值仿真数据对比得到,该方法可以准确计算任意入射波激励下线缆终端负载上的电流响应且计算效率高,可用于腔体内场线耦合的研究。 相似文献
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Neglecting the velocity field perturbation, we examine the current exclusion contribution to the magnetic distortion field H?1 along the symmetry axis of a ?streamlined? enclosure in the shape of a general body of revolution. In contrast to the case of a spherical enclosure where all orientations of the (unknown) unperturbed current density J?o relative to the enclosure surface are equivalent, for the present geometry the relative orientation of J?o must be specified. On the symmetry axis (z-axis) the component of the distortion field parallel to that axis vanishes independent of the orientation of J?o. In regard to field gradients, all diagonal elements of the gradient dyad similarly vanish. However, only the combination ?H?x/?y + ?H?y/?x vanishes independent of orientation. Here (x, y) denote any two orthogonal directions perpendicular to the symmetry axis. 相似文献
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《Power Electronics, IEEE Transactions on》2008,23(6):2681-2693
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孔径抖动对中频采样系统信噪比影响的研究 总被引:12,自引:0,他引:12
孔径抖动对中频(或射频)带通采样系统信噪比的影响非常严重.理论上,尽管相同带宽的中频信号和基带信号可以用相同的频率进行采样,但中频采样受孔径抖动等因素的影响更大,其采样技术要求也更高.如果在中频采样系统中解决不好孔径抖动问题,很可能根本采集不到正确的信号.本文通过分析孔径抖动产生的原因,孔径抖动与ADC (模数转换器)的信噪比以及与被采样信号上限频率之间的关系,找出了由孔径抖动决定的被采样信号的上限频率与ADC模拟带宽之间存在差距的原因,并发现了过采样率与处理增益及孔径抖动之间的关系.最后,介绍了几项减小孔径抖动的具体措施. 相似文献
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《Antennas and Propagation, IEEE Transactions on》2009,57(12):3835-3846