曹乐 周远国 付周兴

摘 要：針对复杂半空间格林函数难以计算的问题，提出一种改进的半空间时域有限差分（FDTD）方法，实现有耗半空间上方细缝金属腔的时域屏蔽效能的高效计算和分析。首先，采用广义传播矩阵法计算半空间复反射系数，再结合傅里叶变换得到半空间时域反射回波。其次，将直接入射波和半空间反射波共同引入到FDTD计算区域，半空间的影响通过反射波体现，从而回避计算形式复杂的半空间格林函数，实现金属腔内部观察点的耦合场及时域屏蔽效能的快速计算。与传统半空间FDTD方法相比，计算方法的误差在0.5%以内，而计算效率提升52%，证明了计算方法的正确性及有效性。结果表明，由于半空间的反射效应，细缝腔体内部观察点的场强增大，时域屏蔽效能显著下降。计算方法可用于半空间背景下腔体时域屏蔽效能的快速分析，从而为电子系统电磁耦合效应的评估提供参考。关键词：时域屏蔽效能;有耗半空间;半空间FDTD;屏蔽腔;电磁脉冲中图分类号：TM 154

文献标志码：A

文章编号：1672-9315（2020）06-01096-06

DOI：10.13800/j.cnki.xakjdxxb.2020.0621开放科学（资源服务）标识码（OSID）：

Evaluation of time-domain shielding effectiveness for

metallic cavities above lossy half-space

CAO Le1，2，ZHOU Yuan-guo2，FU Zhou-xing1

（1.

College of Electrical and Control Engineering，Xian University of Science and Technology，Xian 710054，China;

2.School of Electrical Engineering，Xian Jiaotong University，Xian 710049，China;

3.College of Communication and Information Engineering，Xian University of Science and Technology，Xian 710054，China）

Abstract：In order to solve the problem that the half-space Green function of complex media is difficult to calculate，an improved half-space FDTD algorithm that avoids the half-space Green function is proposed to achieve the efficient computation analysis of the time-domain shielding effectiveness（SE）of the metallic cavities above the lossy half-space.Firstly，the generalized transition matrix method and Fourier transform are used to calculate the reflected wave of half-space.Secondly，with the direct incident wave and the reflected wave  introduced into the calculation region，the coupling field of the observation point inside the cavity under different incident conditions is calculated and analyzed.Compared with the traditional half-space FDTD method，the calculation error here is within 0.5%，and the calculation efficiency is increased by 52%，which proves the correctness and effectiveness of this method.The numerical results show that due to the reflection effect in the half space，the field strength increases，and the time-domain shielding effectiveness decreases significantly.The method in this paper can be used to quickly analyze the shielding effectiveness of the cavity in the time domain in the half-space background，thus providing a reference for the evaluation of the electromagnetic coupling effects of electronic systems.

Key words：time-domain shielding effectiveness;lossy half-space;FDTD method;shielding enclosure;electromagnetic pulse

0 引 言

金属屏蔽腔是电磁兼容设计与防护中保护电子设备、器件不被电磁脉冲干扰的重要手段。然而，为了保障电子设备的正常工作，屏蔽腔往往需要开各种类型的孔缝，而这些孔缝将使得电磁脉冲能量得以进入到电子设备内部。通过这样的“后门”耦合方式进入到电子设备的能量分布在整个系统内部，在特定频率下易发生共振而引起强耦合。……