Читать книгу Introduction To Modern Planar Transmission Lines - Anand K. Verma - Страница 158

The magneto‐dielectric (MD) materials have both electric and magnetic properties. These materials are characterized by the simultaneous presence of permittivity and permeability tensors. These tensors for uniaxial MD materials are expressed as follows:

(4.2.13)

The above‐given expressions for the uncoupled independent relative permittivity and permeability tensors show that there is no coupling between the electric and magnetic fields. Ferrites have such property. However, ferrites are very lossy at microwave frequency. The low‐loss MD materials are synthesized by mixing ferrites/hexaferrite and their composites with a polymer as a host medium [J.3]. The periodic structures are embedded in the host medium to engineer MD materials for antenna applications in VHF and UHF bands [J.4]. The metamaterial composites are also MD materials with simultaneously negative permittivity and permeability in a certain frequency band.