Complex permittivity and permeability of metallic magnetic granular composites at microwave frequencies

Abstract

The complex permittivity and permeability of composites consisting of metallic magnetic particles (carbonyl-iron-particles (CIPs)) embedded in a dielectric matrix (epoxy resin) have been studied at microwave frequencies. Composites with different volume fraction (5–60%) of magnetic particles have been fabricated and their complex permittivity and permeability have been measured. The concentration dependence of permittivity and permeability has been analysed using various effective medium theories. We have found that only the general Bruggeman formula describes composites very well over a wide range of concentrations used in this study. The extracted permittivity and permeability of CIPs are consistent with those reported.