Higher order large-domain FEM modeling of 3-D multiport waveguide structures with arbitrary discontinuities

• Published in: IEEE transactions on microwave theory and techniques Vol. 52; no. 6; pp. 1608 - 1614
• Main Authors: Ilic, M.M., Ilic, A.Z., Notaros, B.M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2004; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Dielectrics; Eigenvalues and eigenfunctions; Electromagnetic analysis; Electromagnetic waveguides; Finite element analysis; Finite element methods; Lagrangian functions; Personal communication networks; Polynomials; Studies; Two dimensional displays; Waveguide discontinuities
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2004.828457

A highly efficient and accurate higher order large-domain finite-element technique is presented for three-dimensional (3-D) analysis of N-port waveguide structures with arbitrary metallic and dielectric discontinuities on standard PCs. The technique implements hierarchical polynomial vector basis functions of arbitrarily high field-approximation orders on Lagrange-type curved hexahedral finite elements of arbitrary geometrical orders. Preprocessing is carried out by a semiautomatic higher order meshing procedure developed for waveguide discontinuity problems. The computational domain is truncated by coupling the 3-D finite-element method (FEM) with a two-dimensional (2-D) modal expansion technique across the waveguide ports. In cases where analytical solutions are not available, modal forms at the ports are obtained by a higher order 2-D FEM eigenvalue analysis technique. The examples demonstrate very effective higher order hexahedral meshes constructed from a very small number of large curved finite elements (large domains). When compared to the existing higher order (but small domain) finite-element solutions, the presented models require approximately 1/5 of the number of unknowns for the same (or higher) accuracy of the results.