The study of the combined influence of substituting ions in multicomponent systems of the type Y3−2xCa2xFe5−x−y−zIny AlzVkO12 is a comparatively difficult task requiring many experiments. Moreover, construction of composition-properties diagrams for such multifactor systems is practically impossible using conventional methods. We used computer processing of the data from a number of experiments in order to determine the overall influence of the substituting components on the microwave properties of such garnets. This enabled us to build mathematical models of the type: Yk=∑bixi+∑bij xixj+∑bijxix jxk. Based on the solution of the equation, triple diagrams were constructed corresponding to strictly defined microwave properties of the system. Thus, the conditions for synthesis are significantly eased and the range for possible microwave applications is increased.