Monodomain NiCuZn Ferrite With High Miniaturization Factor and Low Magnetic Loss at 200 MHz for Antenna Miniaturization

摘要

Monodomain NiCuZn ferrites were investigated for use in the design of a high-efficiency terrestrial digital multimedia broadcasting antenna with reduced physical dimensions. The results show that the reported monodomain design is effective. Specifically, monodomain ferrite with 1 wt% Co₂O₃ doping has a high miniaturization factor (~14) and very low loss factors (tan δ_μ = 0.017 and tan δ_ε = 0.012, respectively). It also reveals equivalent permeability and permittivity (μ' = 14.05 and ε' = 14.12, respectively) at the frequency of 200 MHz, implicating the convenient impendence match in the antenna application and consequent miniaturization. The magnetic spectra of the monodomain samples were studied with a numerical fitting method to obtain guidelines for preparing high-quality materials. The results indicate that it is necessary to lower relaxation frequency ωr and maintain the other dispersion parameters as moderate to achieve a high real part of permeability and low tan δ_μ. Furthermore, we demonstrate that appropriate Co₂O₃ doping is a feasible way to adjust the dispersion parameters.