Investigation of magnetic properties and microwave resonance phenomena in nanocomposites based on opal matrices containing the particles of intermetallide of Fe3Ni2 and FeNi3 is carried out. The interactions which lead to the resonance changes of transmission and reflection coefficients are determined. Electromagnetic properties are measured in the millimeter frequency range. Special attention is paid to comparison between static and dynamic magnetic properties of nanocomposites. Frequency dependences of magnitude of lines of resonance features are obtained. Spectra of resonance and antiresonance are studied. The conditions when the magnetic antiresonance is observed are clarified. The X-ray phase analysis of the nanocomposites is performed and their structure is studied. (C) 2017 Elsevier B. V. All rights reserved.