Polymer Nanocomposites with Hybrid Fillers as Materials with Controllable Electrodynamic Characteristics for Microwave Devices

The results of investigation of microwave electromagnetic properties in wide frequency range (1–67 GHz) of the hybrid polymer composites based on combined introduction of ferrite and MWCNTs nanoparticles are presented. The surge in 3–5 orders of the conductivity value has been founded in MWCNTs/Fe3O4 (BaFe12O19)/epoxy composites with 2 and 5 wt. % of MWCNTs as compared with MWCNTs/epoxy composites, and these changes are more considerable for lower content of MWCNTs in the epoxy matrix. The addition of 30 wt. % of Fe3O4 (BaFe12O19) nanoparticles to MWCNTs/epoxy composites leads to the significant increase of the complex permittivity values and to the frequency shift of relaxation maximums. The natural ferromagnetic resonance was revealed as the main mechanism of magnetic loss in MWCNTs/Fe3O4/epoxy composites at frequencies up to 10–12 GHz while the eddy current induced mechanism becomes the dominant in magnetic loss at the further frequency increase. The natural ferromagnetic resonance determines the character of magnetic loss in BaFe12O19-filled composites in the whole investigated frequency range.