Ultra wideband permeability in micron and nanometer scale two and three phase ferrite, Fe and magnetite composites

Data presented in this paper are appropriate for microwave applications to filters, isolators, EMI materials and antenna substrates. Measured, frequency dispersive magnetic susceptibility data are presented for dielectric composites containing a wide range of volume fractions of different magnetic particulate types: Ni_.32Zn_.48Cu_.12 Fe₂O₄, Ni Mn_.02Fe_1.9O₄: 1.4micron diameter Fe: micron and nanometer scale Fe₃O₄; and three phase composite with Fe and Ni_.32Zn_.48Cu_.12Fe₂O₄. Permeability data of fully dense ferrites are also presented. Properties were measured with permeameter and/or 7mm coaxial line fixtures from 0.001 to 18 GHz. Permeability data were fit to Lorentzian forms. The seven composite types and fully dense ferrite data fits form the basis for comparison of magnetic Maxwell Garnett and Bruggeman effective media theory predictions of susceptibility and volumetric scaling of resonant and relaxation frequencies. The presented data and analysis evaluate theory-model predictions at micron and nanometer scales for a wide range of magnetic particulate types, volumetric concentrations and for multi-phase magnetic composites.