The paper presents the analysis of the structure and electromagnetic properties of magnetodielectric composite material polymerized under the influence of the external magnetic field. The structure, phase composition and magnetic properties are determined for Z-type barium ferrite employed as a filling material in the production of test specimens. It is shown that the external magnetic field has an effect on the structure of this composite material. The proposed treatment technique allows fabricating test specimens with both magnetic and dielectric anisotropy parameters.