Investigations on the Effective and Unified Measurements Method of The Electromagnetic Shielding Effectiveness Using a Small-sized Sample

主要研究结果如下：1.提出了电磁屏蔽效能SE的统一表达式。近场SE与电磁场源和观测点的类型、位置或布置密切相关。但是，远场SE，即对平面波的无限大屏蔽板的SE，与它们无关。因此，在远场SE中采用统一的SE表达式是合适的。远场SE的测量需要很大的空间，而近场SE的测量则不需要。因此，测量是近场SE所需的。推导了近场SE和远场SE的近似换算公式，并通过理论和数值分析估算了屏蔽板的面积大小。并通过实验和测量得到了验证。结果表明，通过对半径小于几十厘米的小尺寸圆形屏蔽板进行近场SE测量，可以估算远场SE，测量系统的空间可以小于1 m^3体积.作为无消声室小型测量空间试验的一部分，我们提出了一种由波源、样品板和金属圆筒内的接收元件组成的装置。导出了这种情况下近场和远场的近似换算公式。

The main results of this investigation were as follows.1. We proposed on the unified expression for the electromagnetic shielding effectiveness SE. Near-field SE is closely related with a type and a position or an arrangement of electromagnetic source and observation point. But, far-field SE which is the SE of an infinite shielding plate for plane wave, is not concerned with them. Therefore, it is adequate that the unified expression for SE should be adopted the far-field SE.2. There needs a large space for the measurements of far-field SE, but dose not for the measurements of near-field SE. Therefore, the measurements are desirable for near-field SE. We derived the approximate conversion formula of the near-field SE and the far-field SE, then we estimated the area size of a shielding plate by theoretical and numerical analysis. They were verified by the experiments and the measurements. As a result, it is shown that the far-field SE can be estimated by the near-field SE measurements of small-sized circular shielding plates less than several ten-centimeter radiuses, and the space of measurement system can be less than 1m^3 volume.3. As a part of the trial for small-sized measurement space without an anechoic room, we propose on the equipment which is consisted of a wave source, a sample plate and a receiving element within a metallic circular cylinder. We derived the approximate conversion formula of the near-field SE and the far-field SE in this case.