Low-loss Cd-substituted Mg ferrites with matching impedance for high-frequency-range antennas

The effects of Cd2+ions on the microstructure,magnetic properties,and dielectric properties of Bi2O3-added MgFe2O4ferrites(CdxMg1-xFe2O4,x=0.00,0.15,0.30 and 0.45) are obtained by adopting the solid-state reaction method at a low temperature(910℃).The objective is to achieve matching impedances,low magnetic and dielectric losses(tan δμand tan δε,respectively),and a relatively large miniaturization factor to reduce antenna size.Experimental results indicate that the cations occupying the tetrahedral(A) and octahedral(B)ion sites are redistributed,resulting in an enhanced super-exchange interaction between the two sublattices.As a result,improved magnetization,including the increase in saturation magnetization(41.74 emu/g) and decrease in coercivity(63.750 e),is realized.The real part of permeability(μ’) also increases with increasing concentration of Cd2+ions.When x is 0.15,matching impedances with equivalent μ’ andε’ values are obtained over a long frequency range(1-150 MHz).Moreover,the formation of a dense microstructure guarantees that losses occur at low orders of magnitude(tan δμ≈10-2and tan με≈10-3).Accordingly,these properties afford wide application perspectives for the proposed compounds in the high-frequency region,i.e.,from high-frequency to very-high-frequency bands.