Embedded-circuit meta-materials for novel design of tunable electro-ferromagnetic permeability, band-gap, and bianisotropic media

Utilizing the available materials in nature one can almost achieve any dielectric material with a relatively large permittivity property, however, the atoms and molecules have more restrictions to design a magnetic medium specially in gigahertz range. It is highly desirable if one could design a material with both permittivity and permeability parameters with a prescribed spectral characteristics. In this paper. we introduce an embedded-circuit meta-material composed of periodic high Q resonant circuits that it offers novel electromagnetic functionalities, namely, simultaneous high permittivity and permeability electro-ferromagnetic property, tunable band-gap, and tunable bianisotropic characteristics The electro-ferromagnetic property refers to a material whose permeability can be varied electronically by an applied DC electric field. The electronic tunability of electro-ferromagnetic, band-gap, and bianisotropic media is achieved by introducing BST varactors in the embedded-circuits. Exact analytical formulations for the effective parameters of the aforementioned embedded-circuit meta-materials are obtained using a transmission line analogy for a medium supporting TEM waves. A powerful finite difference time domain numerical technique is also employed to verify the analytical formulations and provide the wideband comprehensive characterization of the complex periodic structure.