Álvaro Gómez

Rigorous analysis of guided wave propagation of dielectric electromagnetic band-gaps in a rectangular waveguide

Guided wave propagation in a Ku-band rectangular waveguide filled with a series of cells of dielectric materials in the Kronig–Penney morphology is examined. Allowed and forbidden bands in these ideal electromagnetic band-gap (EBG) filters are obtained for the TE z and TM z propagation modes by invoking the Floquet theorem. Real EBG structures, with a finite number of unit cells, are also studied using the scattering matrix technique. As the number of unit cells in a real structure increases, its transmission characteristics converge to those of its ideal analogue.

Comments on "A comprehensive study of discontinuities in chirowaveguides"

For original article by T.X. Wu and D.L. Jaggard see ibid., vol.50, no.10, p.2320-30, Oct. 2002.

New formulation of the coupled mode method for the analysis of chirowaveguides

In this communication we present a formulation of the Coupled Mode Method (CMM) which is different from the one normally used in the literature for solving chirowaveguides. An essential step in the development of the CMM is the way in which the longitudinal components of the electromagnetic field are related to the transverse components of the electromagnetic field. An approach which involves some previous manipulation of the constitutive relations is normally used. This gives a slow convergence of the propagation constants. In previous works, involving isotropic and anisotropic dielectric guides, we have shown that a different way of using the constitutive relations produces faster convergence of the propagation constants to the correct results for the different modes. Following this approach, we show here how this formulation can be applied to a parallel plate waveguide partially filled with different slabs of chiral media. Our results show that the predictions are confirmed in the same way as for anisotropic media.

Analysis of waveguides with periodic layered mediums as electromagnetic band-gap structures

Electromagnetic band-gap structures (EBG) have received considerable attention in the microwave regime, due to their tremendous potential for different applications. In this communication, guided wave propagation in parallel-plate, rectangular and circular waveguides with Kronig-Penney morphology is considered. Propagation modes in these waveguides are classified as either transverse electric (TE) or transverse magnetic (TM) with respect to the propagation direction. At frequencies above the modal cut-off frequencies in the considered waveguides, band gaps exists wherein propagation is forbidden. The allowed and forbidden bands are obtained for the TE and TM propagation modes, after invoking the Bloch theorem. From the study of the ideal EBG structures, the dependencies of the locations and the widths of the band gaps -- on the modal order, the waveguide geometry and dimensions, the permittivity contrast and the relative volumetric proportion of the two materials constituting the unit cell of the EBG structure -- are deduced. Also, propagation in the corresponding real EBG structures, with finite numbers of unit cells, is studied using the scattering matrix technique. As the number of unit cells in a real structure increases, its transmission characteristics converge to those of its ideal EBG analog in the band gaps.