非全屏蔽式动车辐射发射测试装置研究

Research on Non-full Shielding Enclosure Test Equipment for Radiation Emission Test of Electric Multiple Units

为较准确地测试出动车(EMU)行进过程中车体最大的辐射场强值,有必要降低背景噪声对测试的影响。引入了一种非全屏蔽箱体,该屏蔽箱体是根据电磁屏蔽理论设计,利用金属外壳、铁氧体层以及泡沫角锥吸波材料的多层复合屏蔽结构,对背景噪声的电场强度进行有效衰减。通过仿真软件对非全屏蔽箱体的抑制能力进行检测,初步得到了屏蔽箱体内部的电场分布情况,以及屏蔽箱体内外空间的电场分布图。测试结果表明,当背景噪声频率为80 MHz^2 GHz时,非全屏蔽箱体中放置测试天线的位置,背景噪声的电场强度会由1 V/m衰减至0.25V/m以下,各频点平均衰减80%以上。对于波源设置在动车车体其他位置,各频点平均衰减至0.1 V/m以下,抑制效果明显。由这些数据结果初步验证了非全屏蔽箱体的引入对于测试动车最大辐射场强的必要性,以及进行实物测试的可行性。

In order to test the maximum electric field strength of electric multiple units（EMU） accurately,it is necessary to reduce the influence of background noise for the test.We proposed a kind of non-full shielding enclosure,which was designed based on electromagnetic shielding theory.The structure of this shielding enclosure is of multilayer composite material shield,and the material consists of metal layer,ferrite absorbing material,and pyramid absorbing materials,and the electric field strength of background noise could be decayed effectively.The suppression ability of non-full shielding enclosure could be detected by simulation software,and the electric field distribution of shielding box inside and outside space both could be obtained preliminarily.The results show that if background noise frequency is among 80 MHz to 2 GHz,the noise electric field strength will be decayed from 1 V/m to 0.25 V/m,and the value decreases averagely about 80% in different frequency points.If the wave source is set in other positions around EMU,the value will decay to 0.1 V/m and lower in different frequency points.The results verify the necessity of the shielding enclosure for the maximum electric field strength of train,and the feasibility of measurement.