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Multiple scattering of parallel cylinders with arbitrary cross section is computed using the T-matrix of each single scatterer and the general translational matrix for cylindrical waves. Usually, the recommended golden rule to compute the translational matrix is Graf’s addition theorem. However, this approach cannot be properly implemented for some geometries, such as in a two-cylinder case when the center of one of them falls within the minimum circular cylinder that circumscribes the other one. In order to overcome this limitation, a transformation between cylindrical waves and plane waves, followed by propagation of the latter, is proposed. The new approach succeeds due to an adequate truncation of the evanescent plane wave spectrum. This strategy is demonstrated by studying the scattering of three infinite elliptic metallic cylinders for different electrical sizes and observing the convergence of the results as a function of the truncated spectrum. Finally, to conclusively show the interest and applicability of the approach, two more complex problems are treated: a group of infinite elliptic metallic cylinders where two different sizes are combined and a practical real-life filter in substrate integrated waveguide (SIW) technology, including several groups of rectangular dielectric cylinders. [ABSTRACT FROM AUTHOR]

We consider multiple scattering among different groups of vias with each group of vias sharing one antipad in planar waveguide. A transformation is used that converts the 2-D discretization and 2-D surface integration of the product of Green's functions and magnetic surface currents into 1-D discretization and 1-D integration of surface charges on the vias and on the ground plane. This is used to calculate the incident fields onto the vias. Based on the incident fields, the Foldy–Lax equations can be solved to calculate the circuit parameters for the problem. We show that the results are superior to the previously used finite difference method. In addition, the group T-matrix method is used to represent a group of vias to account for the scattering among different groups of vias. Results are illustrated for various cases of multiple vias up to 20 GHz. Results show the accuracy of the method even to very closely spaced vias when they are separated by merely 1 mil. Numerical results are in excellent agreement with ANSOFT HFSS. [ABSTRACT FROM AUTHOR]