Abstract-Guided-wave propagation in chiral H-guides is analyzed, using a building-block approach. In a first stage, a 2D chiral parallel-plate waveguide is studied using a lossless frequency dispersion model for the optically active medium, where the constitutive chiral parameter is assumed to be dependent on the gyrotropic parameter. In the second stage, the mode matching technique and the transverse resonance method are used to characterize the 3D structure. A full parametric study is presented for a fixed frequency. The operational and dispersion diagrams for the chiral H-guide are presented. By replacing the common isotropic slab with a chiral slab, chirality provides an extra degree of freedom in the design of new devices.
Abstract-In this article the influence of both dispersion and losses on waveguides with metamaterials is investigated. The analysis is focused on surface waveguides (planar interfaces and grounded slabs) containing either double-negative (DNG) or chiral metamaterials. The main goal is to show how the combined effect of material dispersion and losses with the structural dispersion affect the solutions of the modal equations. It is shown that this interplay is essential to obtain a correct modal analysis of these waveguides. Namely, the overall behavior can qualitatively change -so that it is not possible to state that the corresponding lossy case -even when a very small amount of losses is introduced -can be interpreted as a small perturbation of the lossless case.
The use of -negative materials with a plasma-like scalar permittivity allows us to achieve this goal, by working in the frequency range where the relative permittivity is lower than one in absolute value, and by adopting suitably low values for the slab width and for the metal-plate spacing. Parametric studies have been presented that illustrate the required thicknesses of the metamaterial layer at different frequencies and the attainable FBW of unimodal propagation.Although encouraging, the results of the present investigation are based on a rather idealized metamaterial model that disregards its actual implementation. Realistic approximations of -negative metamaterials based, e.g., on arrays of wires embedded in a host dielectric require that anisotropy and also spatial dispersion be taken into account in a homogenized equivalent model [13]. A study based on such more refined models and on full-wave simulations of actual metamaterial structures will be the subject of future work.
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