DISPERSION CHARACTERISTICS OF THE COMPLEX PERMEABILITY PERMITTIVITY OF NI-ZN FERRITE-EPOXY COMPOSITES

The effects of volume fraction and particle size of ferrite on the ele ctric and magnetic properties of epoxy composites containing Ni-Zn fer rite were investigated. The composites were prepared by the cement mix ed method and shaped as coaxial, toroidal and disc types. The complex permeability and permittivity were measured using an impedance-gain ph ase analyser (HP4194A) and a network analyser (HP8753C) in the frequen cy range 1 MHz-5 GHz. The complex permeability of the composites was f ound to increase as the ferrite content increased, and was characteris tic of the frequency dispersion. A model to describe the frequency dis persion characteristics of the composite, which was a function of the ferrite content, is proposed here. The complex permittivity of the com posite was found to be dependent mainly on the volume fraction of the ferrite and was relatively independent of frequency and particle size of the ferrite.