Ba2Zn2Fe12O22 − Spinel Ferrite Composites for Magneto-Dielectric Resonator Antenna Application

Abstract

Magneto-dielectric (MD) ferrite materials have been attracting great attention as promising candidates for communication applications, due to their significant advantages for antenna miniaturization and bandwidth enhancement [1-4]. This article examines the potential of the Zn2Y hexagonal and spinel ferrite composite; (Ba2Zn2Fe12O22)1− x(MFe2O4)x (where M=Co, Ni, Zn, Mg) as MD antenna material. Composites were synthesized by one-pot coprecipitation route. The XRD results demonstrated the coexistence of hexagonal and cubic spinel ferrite phases after sintering at 1200 ◦C/4 h. All composites showed a smooth M-H loop due to the interfacial growth of two different types of ferrite grains leading to a strong exchange coupling between spinel and Zn2Y ferrites. The permittivity of the composites is in the range 10–25 (Table 1), while the permeability is between 14 to 20 at 100 MHz. Miniaturization factor (n) is in the range 14 to 20 (Table 1) and characteristic impedance (Zi) is ~1.0 for composites due to equivalent ε and μ values. A MD resonant antenna (MDRA) operating at ~5 GHz was designed, fabricated (Fig. 1(B)), and measured based on the composite ferrite. Fig.1(A) shows the return loss behaviour for different compositions. (Zn2Y)0.6(NiF)0.4 and (Zn2Y)0.6(CoF)0.4 compounds have better radiation efficiency, broader bandwidth and omnidirectional radiation pattern (Fig.1(C)). In conclusion, the composites may be the promising candidates for miniaturized MDRA application.