It has been found that if magnetic materials isolate in dielectric medium, permeability of composite material doesn't obey Lichtenecker's 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-SiO 2 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 SiO 2 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.
- Composite electromagnetic wave absorber
- Ni-Zn ferrite
ASJC Scopus subject areas
- Electrical and Electronic Engineering