A new method for solving irises in waveguides

Citation

Sheiman, Arthur E. (1993) A new method for solving irises in waveguides. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6ptc-ac45. https://resolver.caltech.edu/CaltechTHESIS:02282011-111234950

Abstract

A new boundary residual mode-matching method is developed to find scattering solutions for an infinitely thin transverse iris (diaphragm) mounted in a waveguide (i.e., junction discontinuities). Differing dielectric constants are allowed on the two sides of the iris, and an optional transverse short placed behind the iris is also treated, allowing solutions useful in understanding planar grids used in microwave/millimeter wave power combining. The new method treats the edge-singularity of the iris (edge-condition) in both the electric and magnetic fields, and at each edge of a multi-edge iris, all simultaneously. This results in a rapidly-converging numerical solution, and oscillation-free transverse (electromagnetic) field plots (not available with methods that ignore singularity extraction). The solution is also free from relative convergence problems. Furthermore, the method when used without singularity extraction results in a formulation that is up to eight times faster than the standard boundary residual method, yet requires only one-fourth the memory, and is simpler to program. Singularity extraction further improves the speed and reduces memory requirements. In addition, extensions are made to Schwinger's variational formulas, resulting in formulas that produce highly-accurate answers for certain problems, even with multi-moding. A new type of problem is introduced, that of a triangular shaped iris, and the complicated inner product integrals are solved analytically in closed rational form. Theory and experiment are compared. A group of computer programs are developed to apply this new method, and the source code is listed and declared as "public domain."

Thesis Files