Study on the Magnetically Tunable Filters Based on Mnn+ and Al3+ Co-Doped YIG Ferrite

The polycrystalline Y₃Fe_5-x-yAl_xMn_yO₁₂ (0.2 ≤ × ≤ 0.8, 0 ≤ y ≤ 0.08) compounds are produced by the solid-state reaction technique. The magnetoelectric properties are studied to satisfy the requirement of microwave devices design. Measured results demonstrate that the saturation magnetization (M_s) is decreased due to Al³⁺ ion substitution, and the dielectric loss tangent (tan δ) is reduced by Mnⁿ⁺ ion substitution. Both substitutions provide more degrees of freedom for the devices design. The magnetically tunable filters are theoretically and numerically analyzed. The frequency tunability of the filters based on Co-doped Y₃Fe_4.52Al_0.4Mn_0.08O₁₂ is 0.47 GHz (8.15%), and the bandwidth in the range is compressed by 0.19 GHz under a bias field of 0 to 700 Oe. The insertion loss is decreased from 3.27 to 0.63 dB with tan δ reduced from 0.02 to 0.002. The performance is also modified by different substitutions, indicating the practical engineering application of Mnⁿ⁺ and Al³⁺ Co-doping.