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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Fast Solution of Volume-surface Integral Equations for Conducting-anisotropic Media
摘要： Electromagnetic problems with both conducting and anisotropic media are formulated by volume-surface integral equations (VSIEs). The conducting medium is described by a surface integral equation while the anisotropic medium is governed by volume integral equations (VIEs) and they are coupled together via produced fields. The VSIEs are usually solved by the method of moments (MoM) in which the electric current density on the conductor surface is expanded by the Rao-Wilton-Glisson basis function while the volumetric flux densities inside the anisotropic medium are represented by the Schaubert-Wilton-Glisson basis function. In this work, we use a point-matching scheme to discretize the VIEs of dielectric part and couple it with the MoM for the conducting part. We also incorporate the hybrid scheme with the multilevel fast multipole algorithm to accelerate the solving process for electrically large problems. A numerical example is provided to illustrate the approach and good results have been obtained.
关键词： multilevel fast multipole algorithm,Volume-surface integral equations,method of moments,conducting-anisotropic media
更新于2025-09-23 15:21:01
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Analysis of Elliptical Waveguides With Anisotropic Dielectric Layers
摘要： Our main objective is to extend the discrete mode matching (DMM) method to analyze multilayered elliptical fibers or transmission lines with elliptical dielectric layers. We generate the formulation for the full-wave equivalent circuit (FWEC) and derive the hybrid matrix elements for the dielectric layers in an elliptical coordinate system and then obtain the system equation of the structure. To demonstrate the technique, we analyze elliptical waveguides and compare the results with the data obtained by other authors and by commercial software.
关键词： numerical analysis,conformal,Multilayered microwave structures,anisotropic media
更新于2025-09-16 10:30:52
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MIXED FINITE ELEMENT METHOD FOR 2D VECTOR MAXWELL'S EIGENVALUE PROBLEM IN ANISOTROPIC MEDIA
摘要： It is well known that the conventional edge element method in solving vector Maxwell’s eigenvalue problem will lead to the presence of nonphysical zero eigenvalues. This paper uses the mixed ?nite element method to suppress the presence of these nonphysical zero eigenvalues for 2D vector Maxwell’s eigenvalue problem in anisotropic media. We introduce a Lagrangian multiplier to deal with the constraint of divergence-free condition. Our method is based on employing the ?rst-order edge element basis functions to expand the electric ?eld and linear nodal element basis functions to expand the Lagrangian multiplier. Our numerical experiments show that this method can successfully remove all nonphysical zero and nonzero eigenvalues. We verify that when the cavity has a connected perfect electric boundary, then there is no physical zero eigenvalue. Otherwise, the number of physical zero eigenvalues is one less than the number of disconnected perfect electric boundaries.
关键词： mixed finite element method,Lagrangian multiplier,2D vector Maxwell’s eigenvalue problem,nonphysical zero eigenvalues,anisotropic media
更新于2025-09-09 09:28:46
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Topological properties of bound states in the continuum in geometries with broken anisotropy symmetry
摘要： Waveguiding structures made of anisotropic media support bound states in the continuum (BICs) that arise when the radiation channel of otherwise semileaky modes is suppressed. Hitherto, only structures with optical axes aligned in symmetric orientations inside the waveguide plane, where BICs appear as lines in the momentum-frequency dispersion diagram, have been considered. Here we address settings where such symmetry is broken and unveil a number of fundamental different features. Weak and strong symmetry-breaking regimes are identified, corresponding to azimuthal and polar optical axes orientation asymmetries, respectively. The azimuthal symmetry breaking is found to still preserve the existence loci of BICs in the momentum-frequency dispersion diagram as lines. However, all possible BICs become interferometric, while the polarization separable states that occur in symmetric settings cease to exist. The polar symmetry breaking has stronger effects and transforms the BICs’ existence loci from lines to points, which correspond to full-vector states that exist at discrete values of the optical axis orientation for a given wavelength. Such transformation results in fundamental changes in the topological properties of the radiated field around the BICs.
关键词： anisotropic media,bound states in the continuum,topological properties,symmetry breaking,waveguiding structures
更新于2025-09-04 15:30:14