Elimination of non physical finite-element solutions for Maxwell equations: applications to three dimensional waveguide junctions

Maxwell's equations can be naturally solved by the finite-element method in either two- or three-dimensional formulations for scattering or guided-wave problems. However, the well-known appearance of nonphysical modes has limited their use. In the present work, this problem has been overcome by using suitable basis functions, i.e. edge elements, which give accurate and reliable approximations of the fields. A general three-dimensional waveguide junction problem is formulated. Numerical results for the S-parameters for two test cases are provided and compared to experimental data and spectral domain approach results. These test cases are a rectangular waveguide T-junction and a finline step discontinuity. Field patterns in cut planes are also shown.<>