Tuning of transmission characteristics of epsilon-near-zero metamaterials by controlling permittivity of embedded defects

In this paper we present the results of analytical and numerical studies on the effect of change of permittivity of embedded defects on the transmission characteristics of epsilon-near-zero (ENZ) metamaterials. We investigated electromagnetic wave transmission in the microwave regime through an isotropic ENZ metamaterial-based waveguide embedded with rectangular defects. We found that by adjusting the permittivity of the defect the transmission coefficient can be adjusted over a wide range, and even total transmission can be achieved. With a single rectangular defect, precise control of its permittivity is necessary to achieve and maintain near-perfect transmission through the waveguide. We found that if two defects are used in the ENZ medium, the range of permittivity for near-perfect transmission can be increased. We have also shown that this increase of permittivity range for total transmission and total reflection is also possible in anisotropic ENZ (AENZ) materials with rectangular defect(s).