共查询到17条相似文献,搜索用时 406 毫秒
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为满足材料强电磁脉冲场屏蔽效能的测试需求,搭建了基于屏蔽暗箱窗口法的材料电磁脉冲屏蔽效能测试系统.首先采用连续波对某种金属织物材料进行了频域测试,通过测试空箱和加载材料内部场强大小,计算了该材料的频域屏蔽效能.然后采用快上升沿电磁脉冲源对该材料进行了时域测试,计算了强场作用下材料的峰值屏蔽效能.对测得的时域信号进行降噪处理和快速傅里叶变换(FFT),得到了该材料频域屏蔽效能曲线,与频域试验所测曲线进行了对比,结果基本一致.实验表明该测试系统能够可靠评价强电磁脉冲作用下材料的屏蔽效能. 相似文献
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为准确评价屏蔽材料在强电磁脉冲环境中的屏蔽效能,提出了一种基于屏蔽暗箱窗口法的材料电磁脉冲屏蔽效能时域测量方法。该方法将带有测试窗口的屏蔽箱体置于GTEM 室内,被测屏蔽材料安装在屏蔽箱的测试窗口上,利用置于腔体中心的单极子天线测量耦合进腔体的电磁脉冲电压波形,对测得的时域电压信号进行快速傅里叶变换( FFT) ,得到了被测材料频域屏蔽效能曲线。与频域测试结果进行了对比,结果基本一致。实验表明该测试系统可以有效减小局部增强效应对测量精度的影响,能够可靠评价强电磁脉冲作用下材料的屏蔽效能。 相似文献
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采用基于有限积分方法的电磁仿真软件CST-MWS建立电磁脉冲辐照条件下材料屏蔽效能测试模型,提出脉冲峰值屏蔽效能和脉冲能量屏蔽效能两个方案来评价材料屏蔽能力,并通过仿真分析了电磁脉冲上升时间和脉宽对屏蔽效能的影响。结果表明,脉冲上升时间相对于脉宽对屏蔽效能的影响较大,上升时间越短,屏蔽效能越高,峰值屏蔽效能高于能量屏蔽效能;脉宽对于材料的峰值屏蔽效能基本没有影响,能量屏蔽效能随着脉宽的增大而减小。 相似文献
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结合GJB151A 中的测试标准,求解平面波照射下飞行器线束电磁敏感度(electromagnetic susceptibility ,EMS)
问题。采用时域有限差分法(Finite-Difference Time-Domain ,FDTD)求解空间电磁场在线束屏蔽层上产生的感应电流,
并将其作为多导体传输线(multi-transmission line ,MTL)方程中的激励源[6],计算线缆电磁脉冲响应。该算法可减少
网格剖分数目,节省计算资源,适合电大尺寸目标中线束问题的求解。最后,利用该方法分析了飞行器屏蔽效能和电
磁脉冲极化方式对线束EMS 的影响,得到了电缆设备端感应电压的频率响应特性。计算结果验证了该方法的高效性和
可行性。 相似文献
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提出了一种获取电子设备壳体屏蔽层外接线缆电磁脉冲耦合响应的计算方法。首先,以壳体屏蔽层为分割点,将贯穿线缆分为内外两部分,根据基本传输线理论和戴维南等效原理,得到内外两段线缆的等效电路模型。然后,利用Agrawal散射电压模型分析了外等效电路的端口负载频域响应,并根据该负载响应得出了内部线缆等效电路的端口负载频域响应。最后,以高空核爆电磁脉冲的IEC标准波形为计算波形,通过傅里叶变换方法求解了内部端口上的时域响应,并分析了线缆几何参数和终端负载对响应波形的影响。 相似文献
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《Electromagnetic Compatibility, IEEE Transactions on》2009,51(2):284-292
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惯性约束聚变(ICF)背景下的激光靶耦合过程产生大量电磁脉冲,对诊断设备的正常运行和测试数据的采集产生不良影响,严重时甚至损害诊断装置。介绍了强激光与金属靶相互作用过程中受激辐射产生等离子体的数学模型,模拟了盘锥脉冲天线的物理模型、三维增益等各项指标,并对打靶过程进行测量,得出电磁辐射电场值,并推导出其频域分布。实验结果显示,影响电磁辐射强度的因素有激光能量、激光打靶方式和入射方向等。对于平面靶,相同靶型和靶材质情况下,不同功率激光与平面靶相互作用发出的电磁脉冲具有相似的频谱和相同的特征频率。诊断结果为激光打靶产生电磁脉冲物理机制研究提供重要实验依据。 相似文献
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Tzong-Lin Wu Wern-Shiarng Jou Dai S.G. Wood-Hi Cheng 《Lightwave Technology, Journal of》2003,21(6):1536-1543
A low-cost plastic package of the standard 1 /spl times/ 9 type with effective electromagnetic (EM) shielding ability is developed. Optical transceiver modules with transmission rates of 155 Mb/s and 1.25 Gb/s are tested to evaluate the EM shielding against emitted radiation from the plastic packaging. The results show that the packaged optical transceiver modules exhibit shielding effectiveness (SE) of over 20 dB. The EM shielding properties of plastic materials consisting of nylon66 and liquid crystal polymer (LCP) with carbon fiber reinforced are investigated. The effects of weight percentage of fibers, carbon fiber length, and material thickness on the SE of the plastic composites are studied both from the plane-wave and near-field sources approaches. The packaged plastic optical transceiver modules with their good SE are suitable for use in low-cost and low electromagnetic interference (EMI) Gigabit Ethernet lightwave transmission systems. 相似文献
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《Electromagnetic Compatibility, IEEE Transactions on》1967,9(2):45-48
It is generally impractical to filter low-frequency electromagnetic pulse (EMP) signals from victim circuits. Twisting signal pair conductors is helpful but often results in insufficient isolation. The remainder must be provided by shielding. Highly permeable ferritic materials have generally been found to provide maximum shielding from low-frequency magnetic fields. It is shown that this may not be the case when the signal source is relatively distant from the shield. With large separation, there appears to be a greatly increased mismatch between the wave impedance at the shield and the intrinsic impedance of the metal. This results in much greater reflection of the impinging wave than occurs for the same signal strength with small source to shield separation. The mismatch is greatest with a highly conductive shield material. All common highly permeable materials have low relative conductivity. High permeability does not improve the shielding effectiveness at low audio frequencies because no significant attenuation occurs as the wave passes through the shield. It is concluded that materials such as copper or aluminum are logical choices for shielding circuits from distant, high-intensity, low-frequency EMP. 相似文献