Ni-Znフェライト, パーマロイを孤立分散させた複合電磁波吸収体の評価

概要

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It has been found that if magnetic materials isolate in dielectric medium, permeability of composite material doesnt obey Lichteneckers law, which is well known to explain permeability and permittivity of composite material. This characteristic leads to absorption of electromagnetic wave above 1 GHz. We proposed isolated model to simulate the frequency dispersion of permeability and developed composite electromagnetic wave absorber made of ferrite-SiO2 or permalloy-polystyrene system in which magnetic materials are isolated. The mechanical milling is employed to isolate magnetic materials in the dielectric medium. Ni-Zn ferrite could be isolated in the SiO2 medium and measured values of the complex permeability were close to simulated ones. As a result, this absorber can absorb electromagnetic wave in the frequency range near 2 GHz. Permalloy particles were insulated by molten polystyrene. Permalloy-polystyrene absorber showed good absorption characteristics in the frequency range between 3 and 8 GHz.
2007-10-01