Local-mode analysis of continuous transitions in rectangular waveguides

A local-modes technique is employed for the rigorous full-wave computer-aided analysis of rectangular waveguide components with continuous variations of the transverse cross section along the propagation direction. Fields in the varying waveguide sections are expanded as a sum of the modes of the locally straight waveguide, which, as a result of the longitudinal variations, are coupled to each other; the coupling coefficients depend on the transition geometry and are easily evaluated analytically. The technique offers considerable efficiency and is particularly suitable for the CAD of a large class of waveguide components like tapers, mitered bends, transitions, etc. Examples of applications and comparisons with reference data are illustrated for the case of H-plane transitions in rectangular waveguides. © 1998 John Wiley & Sons, Inc.