Frequency dispersive complex permittivity and permeability of ferromagnetic metallic granular composite at microwave frequencies

► Study on frequency dispersive properties of carbonyl iron/resin composite at 1-18 GHz. ► Intrinsic properties of carbonyl iron particles were extracted and analyzed. ► Effective properties of the composite were correctly described by the Mclachlan formula. ► The Mclachlan formula was proved to be invariable versus frequency for dispersion mediums.