Low loss factor Co2Z ferrite composites with equivalent permittivity and permeability for ultra-high frequency applications

Abstract

Ferrite composites of nominal composition Ba3Co2+xIrxFe24−2xO41 were studied in order to achieve low magnetic and dielectric losses and equivalent permittivity and permeability over a frequency range of 0.3–1 GHz. Crystallographic structure was characterized by X-ray diffraction, which revealed a Z-type phase accompanied by increasing amounts of Y-type phase as the iridium amount was increased. The measured microwave dielectric and magnetic properties showed that the loss tan δε and loss tan δμ decreased by 80% and 90% at 0.8 GHz with the addition of iridium of x = 0.12 and 0.15, respectively. An effective medium approximation was adopted to analyze the composite ferrites having mixed phase structures. Moreover, adding Bi2O3 enabled equivalent values of real permittivity and real permeability over the studied frequency range. The resultant data give rise to low loss factors, i.e., tan δε/ε′ = 0.008 and tan δμ/μ′ = 0.037 at 0.8 GHz, while characteristic impedance was the same as that of free space.