Finite element modeling of electromagnetic radiation

Download

index.pdf

Date

2007

Author

Özgün, Özlem

Metadata

Show full item record

Item Usage Stats

336
views

355
downloads

The Finite Element Method (FEM) is a powerful numerical method to solve wave propagation problems for open-region electromagnetic radiation/scattering problems involving objects with arbitrary geometry and constitutive parameters. In high-frequency applications, the FEM requires an electrically large computational domain, implying a large number of unknowns, such that the numerical solution of the problem is not feasible even on state-of-the-art computers. An appealing way to solve a large FEM problem is to employ a Domain Decomposition Method (DDM) that allows the decomposition of a large problem into several coupled subproblems which can be solved independently, thus reducing considerably the memory storage requirements. In this thesis, two new domain decomposition algorithms (FB-DDM and ILF-DDM) are implemented for the finite element solution of electromagnetic radiation/scattering problems. For this purpose, a nodal FEM code (FEMS2D) employing triangular elements and a vector FEM code (FEMS3D) employing tetrahedral edge elements have been developed for 2D and 3D problems, respectively. The unbounded domain of the radiation/scattering problem, as well as the boundaries of the subdomains in the DDMs, are truncated by the Perfectly Matched Layer (PML) absorber. The PML is implemented using two new approaches: Locally-conformal PML and Multi-center PML. These approaches are based on a locally-defined complex coordinate transformation which makes possible to handle challenging PML geometries, especially with curvature discontinuities. In order to implement these PML methods, we also introduce the concept of complex space FEM using elements with complex nodal coordinates. The performances of the DDMs and the PML methods are investigated numerically in several applications.

Subject Keywords

Electronics.

URI

http://etd.lib.metu.edu.tr/upload/3/12608290/index.pdf
https://hdl.handle.net/11511/17052

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Design and implementation of microwave lumped components and system integration using MEMS technology Temoçin, Engin Ufuk; Akın, Tayfun; Department of Electrical and Electronics Engineering (2006) This thesis presents the design and fabrication of coplanar waveguide to microstrip transitions and planar spiral inductors, and the design of metal-insulator-metal capacitors, a planar band-pass, and a low-pass filter structures as an application for the inductors and capacitors using the RF MEMS technology. This thesis also includes a packaging method for RF MEMS devices with the use of “benzocyclobutene” as bonding material. The transition structures are formed by four different methods between coplanar ...
Analysis of coupled lines in microwave printed circuit elements Piroğlu, Şefika Özkal; Dural Ünver, Mevlüde Gülbin; Department of Electrical and Electronics Engineering (2007) Full wave analysis of microstrip lines at microwave frequencies is performed by using method of moments in conjunction with closed-form spatial domain Green’s functions. The Green’s functions are in general Sommerfeld-type integrals which are computationally expensive. To improve the efficiency of the technique, Green’s functions are approximated by their closed-forms. Microstrip lines are excited by arbitrarily located current sources and are terminated by complex loads at both ends. Current distributions ...
Magnetic resonance current density imaging using one component of magnetic flux density Ersöz, Ali; Eyüboğlu, Behçet Murat; Department of Electrical and Electronics Engineering (2010) Magnetic Resonance Electrical Impedance Tomography (MREIT) algorithms using current density distribution have been proposed in the literature. The current density distribution can be determined by using Magnetic Resonance Current Density Imaging (MRCDI) technique. In MRCDI technique, all three components of magnetic flux density should be measured. Hence, object should be rotated inside the magnet which is not trivial even for small size objects and remains as a strong limitation to clinical applicability o...
Three dimensional laminar compressible navier stokes solver for internal rocket flow applications Coşkun, Korhan; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2007) A three dimensional, Navier-Stokes finite volume flow solver which uses Roe’s upwind flux differencing scheme for spatial and Runge-Kutta explicit multi-stage time stepping scheme and implicit Lower-Upper Symmetric Gauss Seidel (LU-SGS) iteration scheme for temporal discretization on unstructured and hybrid meshes is developed for steady rocket internal viscous flow applications. The spatial accuracy of the solver can be selected as first or second order. Second order accuracy is achieved by piecewise linea...
Ray based finite difference method for time domain electromagnetics Çiydem, Mehmet; Koç, Seyit Sencer; Department of Electrical and Electronics Engineering (2005) In this study, novel Ray Based finite difference method for Time Domain electromagnetics(RBTD) has been developed. Instead of solving Maxwell̕s hyperbolic partial differential equations directly, Geometrical Optics tools (wavefronts, rays) and Taylor series have been utilized. Discontinuities of electromagnetic fields lie on wavefronts and propagate along rays. They are transported in the computational domain by transport equations which are ordinary differential equations. Then time dependent field solutio...

Citation Formats

Ö. Özgün, “Finite element modeling of electromagnetic radiation,” Ph.D. - Doctoral Program, Middle East Technical University, 2007.