Layered dielectric–magnetic composite structures for Rf-applications

In this paper multilayer magnetic–dielectric composite structures for high frequency applications are introduced. The 0–3 type dielectric and magnetic composites with homogeneously distributed ceramic inclusions were fabricated by mixing extrusion and injection moulding. Magnetic Yttrium Iron Garnet (YIG) and Z-type Hexaferrite (HexaZ) as well as paraelectric Barium Strontium Titanate (BST) powders were used to enhance the permittivity and permeability of the composites. The magnetic–dielectric multilayer composites were constructed by hot-laminating magnetic and dielectric layers in turn to create a solid 2-2 type composite structure. The microstructure, high frequency dielectric and magnetic properties of individual layers and 2-2 composites were investigated and measured. The measurement results indicate that such multimaterial multilayer structures are good candidates for components with reduced dielectric and magnetic losses. Moreover, the observed good frequency stability and the cut-off frequencies above 1 GHz suggested that the composites could be utilized in, e.g., sophisticated functional circuit boards and RF devices.