著者

小塚 洋司

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.21, no.10, pp.1159-1166, 1997-10-01

参考文献数

33

被引用文献数

23

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Demand for ferrite EM-absorbers is going to increase, particularly in the field of EMC (electro-magnetic compatibility) technology. They are used for anechoic chambers, for example, and to prevent TV ghosting,forged echos in ships' rader signals, and EM-wave leakage from various electric devices. The fundamental principle for the construction of a ferrite EM-wave absorber is based on the idea of a "magnetic resistive sheet" backed with a conductive plate. However, various types of ferrite absorber that depart from this principle have been developed recently. For instance, double-layered absorbers, consisting of carbon and ferrite materials, and grid ferrite absorbers are widely used for anechoic chambers. EM-wave absorber consisting of a concrete panel and a ferrite plate, or of a concrete panel containing ferrite particles to prevent TV ghosting, have been developed as materials for building walls. These ferrite materials include, sintered soft ferrite, rubber ferrite, plastic ferrite, and by-product ferrite. This paper first describes the fundamental principle of a ferrite absorber's constraction and reviews trends in research on ferrite EM-wave absorbers. In response to recent broad EMC technology trends in EM-absorbers, simple methods for improving and changing the frequency characteristics of ferrite absorbers are introduced, such as the use of magnetized ferrite, ferrite combined with other materials, and ferrite with small holes.