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A multitrace surface integral equation (MT-SIE) solver is proposed to analyze electromagnetic field interactions on composite devices involving magnetized and nonmagnetized graphene sheets. The computation domain is decomposed into two subdomains: an exterior subdomain that represents the unbounded background medium where the device resides in an interior subdomain that represents the dielectric substrate. Resistive Robin transmission conditions (RRTCs) are formulated to describe the infinitesimally thin graphene sheet that partially covers the surface between the two subdomains. On the rest of this surface, traditional Robin transmission conditions (RTCs) are enforced. The electric and magnetic field equations are used as the governing equations in each subdomain. The governing equations of a subdomain are locally coupled to the governing equations of its neighbor using RRTCs and RTCs. The accuracy and the applicability of the proposed MT-SIE solver are demonstrated by various numerical examples. [ABSTRACT FROM AUTHOR]

In this article, a local coupling multitrace domain decomposition method (LCMT-DDM) based on surface integral equation (SIE) formulations is proposed to analyze electromagnetic scattering from multilayered dielectric objects. Different from the traditional SIE-DDM, where the interactions between subdomains are accounted for using global radiation coupling, LCMT-DDM uses a local coupling scheme. The original multilayered object is decomposed into several independent domains, i.e., the exterior region (free space) and many homogeneous interior regions (dielectrics). The boundaries of subdomains are all touching faces, where only the Robin transmission conditions (RTCs) are enforced to ensure the field continuity. Hence, each subdomain only couples with its neighboring regions, which makes the DDM system a highly sparse matrix, especially when the number of subdomains is large. In each subdomain, the electric-field integral equation (EFIE) and the magnetic-field integral equation (MFIE) for dielectrics are used as the governing equations. By imposing RTCs, well-conditioned equations are formed in each subdomain without invoking the combined-field integral equation (CFIE), which usually causes accuracy issues in dielectric modeling. Since the subdomain matrices are diagonally dominant, the flexible generalized minimal residual (FGMRES) technique is used to accelerate the iterative solution of the whole DDM system. Moreover, an effective preconditioner that can be recursively constructed is proposed. [ABSTRACT FROM AUTHOR]

In this communication, a new multiple-traces Poggio–Miller–Chang–Harrington–Wu–Tsai (MT-PMCHWT) equation is proposed to simulate the electromagnetic scattering from microstrip structures. Based on the surface equivalent principle, the original object can be decomposed into two independent domains, i.e., the exterior region (free space) and interior region (microstrip). Different from the traditional EFIE-PMCHWT method, in this new multiple-traces method, dielectric surface is discretized with two pairs of meshes, and Robin transmission conditions (TCs) are enforced on the interface between the exterior and interior regions to ensure the continuity of fields. In comparison with the traditional EFIE-PMCHWT, this new MT-PMCHWT has a better iteration convergence property. Additionally, a new multiple-traces electric field/combined field integral equation with better iteration convergence is also proposed. Because the continuity of fields is ensured by TCs, the exterior and interior regions can be discretized with nonconformal meshes, which improves the flexibility and efficiency of the proposed methods substantially. [ABSTRACT FROM AUTHOR]

Due to simplicity, hybridization of geometrical optics (GO) and physical optics (PO) based on ray tracing has been widely used for fast scattering analyses. However, when targets of curved concavities are discretized by flat facets, the loss of divergence factor (DF) will degrade the simulation accuracy. To remedy this loss, a simple and efficient factor, entitled virtual divergence factor (VDF), is proposed to play the role of DF. To prove the validity of VDF and simulate the scattering of concave complex targets, a hybrid method of GO/PO and physical theory of diffraction (PTD) is elucidated. With VDF correction, several typical targets, including a S-shape cavity, are simulated by this hybrid method. In comparison to multilevel fast multipole algorithm (MLFMA) or measurements, the validaty of VDF is fully demonstrated by good agreements and the excellent performance relative to DF on canonical surfaces, where the great efficiency and flexibility of this hybrid method are also shown. Moreover, one interesting and important issue, the dependance of field convergence on the maximum number of ray reflections, is also investigated for the first time. [ABSTRACT FROM PUBLISHER]

In this communication, a novel domain decomposition method (DDM) based on integral equation is developed for solving scattering problems of very thin, conducting cavity. By imposing equivalent electric and magnetic currents on the aperture, the original problem is transformed into interior and exterior problems. Different from traditional method based on interior-exterior equivalence principle, this work couples the exterior and interior problems only through the transmission condition on the aperture. Based on this DDM, a well-posed combined field integral equation (CFIE) is successfully developed to realize fast solution of electromagnetic scattering from open-ended cavity with extremely thin or zero thickness. Compared to the electric field integral equation, the proposed CFIE significantly improves the convergence rate of iterative solvers. Numerical results are given to demonstrate the validity and advantages of the present method. [ABSTRACT FROM PUBLISHER]