Study on Achievement of a High-performance Test Room for Measuring Electromagnetic Disturbance

以实现高性能电磁干扰测试室为目标，对电磁暗室和磁屏蔽室进行了研究，取得了以下成果：(1)实现了高性能电波暗室，建立了以泡沫铁氧体为新型吸声材料的电波暗室，证实了吸波材料厚度可以减小到10 cm，是传统吸波材料的1/10。(2)电波暗室电磁场的模拟利用射线追踪法建立了200 MHz以上频率范围内电波归一化场地衰减(NSA)的计算方法，并用同样的计算方法从理论上探讨了改善电波暗室NSA的方法。对于200 MHz以下的频率范围，我们开发了一种基于FDTD方法的NSA计算方法。(3)磁屏蔽室用磁性材料我们制备了磁性介质超晶格，并发现在保持磁性的同时控制它们的电阻是可能的。此外，在极低的温度下，我们发现了一种被认为是一种新现象的效果，这种现象使渗透率比同类传统材料增加了一百多倍。

With the objective of achieving a high-performance test room for measuring electromagnetic disturbance, an electromagnetic anechoic chamber and a magnetic shield chamber are investigated.The results obtained are as follows :(1) Realization of High Performance Anechoic Chamber ; With the construction on an anechoic chamber which uses foamed ferrite as new absorbing material, it is confirmed that the absorber thickness can be decreased to lO cm, which is 1/10 that of the conventional absorber. This is the first in the world to realize a thickness of only lO cm in the frequency range of 30 MHz to 10 GHz.(2) Simulation of Electromagnetic Field for Anechoic Chamber ; We developed a calculation method of NSA (Normalized Site Attenuation) in the frequency range above 200 MHz by using ray tracing method and theoretically investigated methods of improving NSA of anechoic chamber using the same calculation method. For the frequency range below 200 MHz, we developed an NSA calculation method using FDTD (Finite Difference Time Domain) method.(3) Magnetic Material for Magnetic Shield Chamber ; We produced magnetic dielectric super lattices and- discovered that it is possible to control their electrical resistance while maintaining the magnetic properties. Furthermore, at extreme low temperatures, we discovered effects which are thought to be the result of a new phenomenon which increases permeability by more than a hundred times that of same-class conventional materials.