【作者】 吴景艳；

【导师】 邹澎；

【作者基本信息】 郑州大学 ， 通信与信息系统， 2004， 硕士

【摘要】 本文简要地分析了FDTD法(时域有限差分法)的基本原理，详细讨论和解决了如何利用该方法计算GHz横电磁波室(GTEM Cell)内场的分布。解决了所涉及的几个关键技术问题，如GTEM Cell内网格剖分的方法、激励源的设置和计算、边界条件的设置(包括金属板表面的边界条件，GTEM Cell内倾斜面的边界条件和吸收边界条件等)、计算参数的设置和峰值检测等。 系统地研究了GTEM Cell内场分布的特点及在其电磁兼容测量中的应用，包括：空腔GTEM Cell内电磁场的数值计算和测量；放入金属DUT(Device Under Test)后GTEM Cell内电磁场的数值计算；以及两者的分析比较，测量结果和计算结果基本吻合。计算结果表明GTEM Cell的有效工作区内，场分布近似为均匀场，场强的变化小于4dB，可以满足电磁兼容测量的要求。放入机箱后，场的纵向分量(z分量)增大了，表明场的模式发生了变化，横电磁波场的特性变差。 为测量不同屏蔽材料屏蔽效果，文中设计了试验用机箱，研究了利用GTEM Cell测量机箱屏蔽效果的方法，并对采用不同屏蔽材料的机箱的屏蔽效果进行了测量，给出了大量的测量数据和一些有价值的结论。对计算机机箱的屏蔽措施进行了研究和改进，系统地分析了机箱需要屏蔽的部位，采取了相应的屏蔽方法。还测量了一般计算机机箱增加屏蔽措施前后的屏蔽效果和在试验中普遍存在的电缆的天线效应的影响。更多还原

【Abstract】 The principle result of the FDTD (Finite-Difference Time-Domain) method is set forth concisely in the thesis. Some key technical problems about using the method to calculate the field distribution in GTEM Cell (GHz transverse electromagnetic transmission cell) are discussed in detail and solved. For example, the gridding dissect; inspiring source’s setting and calculating; boundary terms’ setting (including boundary terms’ on slat exterior, boundary terms of slope slant inner GTEM Cell and absorbing boundary terms); calculating parameter’s setting and inspecting peak value etc are involved.The feature of the field distribution in GTEM Cell and its application in EMC is systematically studied here, such as: the numerical value calculation and measure in hollow GTEM Cell; the numerical value calculation in GTEM Cell when metal DUT added; and the analyse and comparison of both results. Through comparison, the calculation results are in accord with the measure results, the field in GTEM Cell’s efficient workground is an equal field. In efficiency workground, when the change of electric field intension is less than 4dB, which can meet the need of EMC measure. When adding the metal case, electric field intension increased. This is because, the region which is not nil between the soleplate and core plate is minished; portrait heft (z heft) accretion. Those indicate that the mode of field changed, characteristic of transverse electromagnetic wave become worse.Shielding measure of computer case is also studied and improved in this thesis. The possible part to be shielded is systematically analyzed, and the shielding method is given relevantly. The case which can be used to do experiments are designed. The method of how to use GTEM Cell to measure the case’s shielding effect is studied. The shielding effect with varies shielding material are measured. Quantities of measurement data and valuable conclusion are given. In the end, this thesis also stated the measurement of the shieldingeffect to common computers before and after adding shielding materials, and the antenna effect of cable that commonly exists in these experiments.更多还原