Low Loss ${\rm NiZn/Co}_{2}{\rm Z}$ Composite Ferrite With Almost Equal Values of Permeability and Permittivity for Antenna Applications

A series of NiZn-ferrite/Co₂Z-hexaferrite composite ferrites were successfully synthesized by the solid-state reaction method for their potential application as magneto-dielectric antenna substrate materials. It is found that, with the increasing amount of NiZn ferrite (x) from 55 wt% to 70 wt%, the real permeability μ´ at low frequencies is improved from ~10 to ~19, while the real permittivity ε´ varies slightly with value around 14. The sample with wt % has almost equal values of μ´ and ε´, large miniaturization factor about 15, as well as sufficiently low dielectric and magnetic loss (1-50 MHz). This composite ferrite is very useful to the design of miniaturized antenna with good impedance-matched to free space.