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

Abstract

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 $\delta _{{\mu }} = 0.017$ and tan $\delta _{{\varepsilon }} = 0.012$ , respectively). It also reveals equivalent permeability and permittivity ( $\mu ^\prime = 14.05$ and $\varepsilon ^\prime = 14.12$ , 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 $\omega _{{{\text{r}}}}$ and maintain the other dispersion parameters as moderate to achieve a high real part of permeability and low tan $\delta _{{\mu }}$ . Furthermore, we demonstrate that appropriate Co2O3 doping is a feasible way to adjust the dispersion parameters.