Ga ions-tailored magnetic-dielectric properties of Mg–Cd composites for high-frequency, miniature and wideband antennas

Abstract Mg ferrites are essential to stabilize the spinel structure of magnetic-dielectric composites. This study investigates the effect of Ga ions on the magnetic and dielectric properties and low-loss characteristics of Mg–Cd composites sintered at low temperature with the addition of 2.5 wt% Bi2O3. The variation in the Ga substitution of Fe at the octahedral site, with x increasing from 0.00 to 0.18 (Mg0.8Cd0.2Fe2-xGaxO4), increases magnetization, which plays the key role in determining the permeability. The real part of the permeability (μ′) of the Ga-substituted ferrites was reported to increase monotonically from 10 H/m to 56 H/m. Meanwhile, the real part of the permittivity (e′) was optimized by the Ga ions. Consequently, relatively matching impedance factor (Z ≈ ≈1.34) and wideband characteristic factor (BWR≈2.5 × 10−3) were obtained to achieve miniaturization and high radiation performance of antennas. Additionally, enhanced magnetization (Ms = 22.32 emu/g, Hc = 55.07 Oe) as well as magnetic (tanδμ∼10−2) and dielectric tangents (tanδe∼10−4-10−3) of low orders of magnitude promise outstanding operating performance in the high-frequency region.