engleski

Physics of Wave Propagation in Miniaturized Metamaterial-based Waveguides: Analytical, Numerical and Experimental Investigation

Recently, it has been observed that a waveguide, transversal dimension of which is arbitrarily smaller than a half of a wavelength supports the propagating modes if it is filled with an anisotropic single-negative (SNG) metamaterial. This counter-intuitive phenomenon is analyzed analytically, numerically and experimentally. An idealized scenario with a lossless, continuous (either mu-negative (MNG) or epsilon-negative (ENG)) filling material is used in the theoretical analysis. It is shown that the equivalent plane waves that make up the waveguide mode are inhomogeneous and this fact is responsible for the propagation below a cut-off. Numerical investigation was performed with the help of commercial FD code and it dealt with the waveguides filled with the realistic metamaterials. The simulation showed a backward-wave propagation band located below the cut-off as it was predicted by a simple homogenized model. Not surprisingly, it was also found that the microscopic (in-cell) field distribution may significantly differ from the distribution in the homogenized waveguide. Several experimental waveguides filled with double-ring resonators (an MNG filling) and the thin wires (an ENG filling) were successfully prototyped and tested in 450 MHz and 8 GHz bands. Measurement results confirmed theoretical and numerical analysis but they also revealed unexpected phenomenon of backward wave-propagation in experimental double-ring MNG filling situated in the free space without any waveguide walls.

metamaterial; waveguide; anisotropy; miniaturization

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