Electromagnetic properties of magnetic epsilon-near-zero medium with dielectric dopants.

Epsilon-and-mu-near-zero (EMNZ) medium which possessing close to zero permittivity and permeability has peculiar electromagnetic properties and can be utilized to design various electromagnetic functional devices. Recent theoretical research shows that EMNZ medium can be achieved by simply doping normal dielectric in an epsilon-near-zero (ENZ) medium, which is easier to obtain than EMNZ medium. Practically, the permittivity will cross zero in the terahertz regime for polar dielectrics and some semiconductors, and in the visible and ultraviolet for the noble metals. While in the microwave band, it is recently found that some magnetic materials can be used to realize the ENZ medium. Here in this paper, we extend the doping theory and propose the similar way for realizing EMNZ property in magnetic ENZ medium by adding dielectric dopant. Both the theoretical analysis and full wave simulation show EMNZ can be achieved by adjusting the parameters of normal dielectric dopants, such as the size, relative permittivity, as well as the number of dopants in a magnetic ENZ with arbitrary value of permeability. To verify the proposed theory, a practical electromagnetic tunneling structure is designed and tested based on an existing magnetic ENZ material through proper dielectric doping. The proposed design method may provide realistic and meaningful guidance for the realization and application of practical EMNZ medium at microwave frequency.