Antonio L. Topa

ELECTROMAGNETIC WAVE PROPAGATION IN CHIRAL H-GUIDES

Guided-wave propagation in chiral H-guides is analyzed, using a building-block approach. In a flrst 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 flxed 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.

Semileaky waves in dielectric chirowaveguides.

The occurrence of semileaky waves in dielectric chirowaveguides is investigated. It is shown that a thinfilm dielectric chiroslabguide with an achiral superstrate and in which both the film and substrate are chiral can support semileaky modes radiating energy into the substrate, provided that the chirality parameters are properly chosen.

Guidance and Leakage Behavior of Uniaxial Ridge Waveguides

This paper addresses the guided-wave propagation in an open uniaxial ridge waveguide. The analysis is focused on the discrete modes, although including both guidance and leakage behavior. It is shown that, beyond a certain critical frequency, the surface guided modes may turn into leaky modes, due to the TE-TM mode coupling at the waveguide lateral boundaries. The numerical results were obtained using a conventional mode matching technique with a finite number of surface waves in each region. The results obtained for the guided modes are validated by comparison with those obtained through a more accurate analysis. The influence of the anisotropy and the geometrical parameters on the attenuation and phase constants of the leaky modes is shown.

ELECTROMAGNETIC WAVE PROPAGATION IN OMEGA WAVEGUIDES: DISCRETE COMPLEX MODES AND APPLICATION TO A RIDGE WAVEGUIDE

This paper addresses guided wave propagation in three- dimensional open omega waveguides. The analysis uses a mode matching technique, is focused on the discrete modes and includes both guidance and leakage behavior. It is shown that, in some ranges of operation, the discrete surface modes turn into leaky modes due to TE-TM mode coupling, an effect already known for isotropic dielectric waveguides. The numerical results show the influence of the medium and geometrical parameters on the attenuation and phase constants of these leaky modes.

Least Squares Boundary Residual Method for the Analysis of Step Discontinuities in Open Chiral Waveguides

Summary We analyse the reflection, transmission and radiation characteristics of a step discontinuity in a grounded chiral slab and we show that the step radiation can be enhanced due to the effect of the chirality. The analysis is performed using a mode matching technique. The fields are expressed in terms of the discrete modes and the continuous spectrum using two subsets of hybrid radiation modes: incident transverse electric (ITE) and incident transverse magnetic (ITM) modes. The scattering matrix of the step is determined by minimizing the boundary residual error in the sense of the least squares. The influence of chirality on the characterization of the step is demonstrated and we show that control of the radiation pattern is achieved, including angle and width of the radiation beam.

Surface and Leaky Modes of Multilayered Omega Structures

We investigate the discrete real and complex solutions of the modal equation of an asymmetric pseudochiral slab waveguide, in which both the film and the substrate are pseudochiral media. When the pseudochiral parameter exceeds a certain transition value, power leakage occurs since one of the characteristic waves ceases to be internally reflected at the film-substrate interface. The analysis includes a parametric study of the effect of the media on the propagation characteristics of multilayered omega structures. The dependence of the propagation characteristics on the frequency is also addressed.

Dispersion and Losses in Metamaterial DNG H-Guides

This article addresses the influence of the metamaterial losses and dispersion on the performance of double negative H-guides. The lossy dispersive Lorentz model is adopted for both the electric permittivity and the magnetic permeability. The dispersion properties of the longitudinal section magnetic modes and their root dynamics in the complex plane of the longitudinal wavenumber are analyzed. To emphasize that the modal characteristics must be analyzed taking losses into consideration, results for the lossless approximation are also presented. Finally, it is shown that the effect of metamaterial losses may suggest some potential applications.

Special Issue of Bianisotropics 2000: Guest Editorial

Summary An introduction to this special issue devoted to Bianisotropics 2000 – 8th International Conference on Electromagnetics of Complex Media, is provided.

COMPLETE SPECTRAL REPRESENTATION FOR THE ELECTROMAGNETIC FIELD OF PLANAR MULTI-LAYERED WAVEGUIDES CONTAINING PSEUDOCHIRAL Ω -MEDIA

A complete spectral representation for the electromagnetic field of planar multilayered waveguides inhomogeneously filled with pseudochiral Ω -media is presented. The problem of guided electromagnetic wave propagation is reduced to an eigenvalue equation related to a 2x2 matrix differential operator. Using the concept of adjoint waveguide, general bi-orthogonality relations for the hybrid modes (either from the discrete or from the continuous spectrum) are derived. For the special case of homogeneous layers the linear operator formalism is reduced to a simple 2 x 2 coupling matrix eigenvalue problem. Finally, as an example of application, the surface and the radiation modes of a grounded pseudochiral Ω -slab waveguide are analyzed.

Metamaterial dispersion and loss in a double negative nonradiative dielectric waveguide

This paper addresses the influence of the metamaterial losses and dispersion on the performance of double negative non-radiative dielectric waveguides. The lossy dispersive Lorentz model is adopted for both the electric permittivity and the magnetic permeability. The dispersion properties of the longitudinal section magnetic modes and their root dynamics in the complex plane of the longitudinal wavenumber are analyzed. Finally, it is shown that the effect of metamaterial losses may suggest some potential applications.