The combined influence of the substitutions and the microstructure on the microwave properties of the garnet system Y32xCa2xFe5‐x‐yVxInyO12 where 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.6 is investigated. It is found that at a certain degree of substitution the main electrophysical parameters of the materials (saturation magnetization Ms, resonance linewith ΔH, dielectric loss angle tangent tg δϵ) are dependent on the microstructure, which can be controled by the sintering temperature. Materials with low magnetic and dielectric losses are obtained.