Metamaterials are composite materials made on a macroscopic level, and provides physical properties that cannot be afforded by naturally occurring materials. In particular, metamaterials can extend the range of electromagnetic properties in materials, as to provide enhanced permittivity and permeability, or negative refractive index. To date, these materials have been explored for use in optical and microwave applications, including band-pass filters and antennas.
Researchers at the University of Michigan have developed a novel artificial electro-ferromagnetic material. The material is designed using a composite mixture of dielectric, ferro-electric, and metallic materials arranged in a periodic fashion. By changing the intensity of an applied DC field, the permeability of the artificial electro-ferromagnetic can be properly varied over a particular range of frequency. The structure shows excellent Electromagnetic Band-Gap (EBG) behavior with a band-gap frequency that can be tuned by changing the applied DC field intensity. The building block of the electro-ferromagnetic material is composed of miniaturized high Q resonant circuits embedded in a low-loss dielectric background. The resonant circuits are constructed from metallic loops terminated with a printed capacitor loaded with a ferro-electric material. Modifying the topology of the embedded-circuit, a bi-anisotropic material (tunable) is examined. The embedded-circuit meta-material is treated theoretically using a transmission line analogy of a medium supporting TEM waves.
Applications and Advantages
- Unique properties applicable in future wireless communication systems
- Simple fabrication
- Multi-band gap or bi-anisotropic properties possible via variable configuration
- Electronically tunable properties: effective permeability, behavior of band-gap(s), or bi anisotropic parameters