Microwave properties of ferromagnetic composites and metamaterials

In this paper, we present our work on ferromagnetic composites for microwave applications [Lebourgeois, R., et al., New ferromagnetic composites for radio-frequency applications. J. Magn. Magn. Mater., 2003, 254–255, 608–611; Adenot, A.L., et al., Tuneable microstrip device controlled by a weak magnetic field using ferromagnetic laminations. J. Appl. Phys., 2000, 87(8), 6914–6916]. The metallic character of ferromagnetic materials led us to use them as inclusions in a composite. We worked on three topologies of composites: laminate, wire and sphere composites. We show the microwave permeability measured on samples representative of these topologies, elaborated from ferromagnetic thin films, glass coated microwires, and polyol powder. Then, we focus on metamaterials, which is a new approach in the field of electromagnetic materials. We illustrated the striking properties of these composites on wire and laminate composite samples. The metamaterial approach is a very efficient tool to control the resonance frequency of the composite material.