High-frequency permeability and permittivity of NixZn(1−x)Fe2O4 thick film

Magnetic materials such as Ni_xZn_(1−x)Fe₂O₄ have resonant frequency in high frequency; therefore, they are more useful especially in microwaves. The Ni_xZn_(1−x)Fe₂O₄ was prepared by the chemical coprecipitation method using citrate precursors, and the fritless thick film was screen printed on alumina substrates. The composition-dependent permeability and permittivity in the high frequency 8–12 GHz are investigated. Using the overlay technique on Ag-thick-film patch antenna, the change in reflectance and transmittance has been measured. The Ni_xZn_(1−x)Fe₂O₄ thick film, when used as overlay on Ag-thick-film patch antenna, changes the resonance characteristics. The changes in resonance frequency, reflectance and transmittance have been used to calculate the permeability and permittivity of the thick film. Zinc-concentration-dependent changes are obtained.