FAST AND ACCURATE MODE-SPECTRUM ANALYSIS OF WAVE-GUIDE STRUCTURES USING A NEW SET OF EDGE-CONDITIONED BASIS FUNCTIONS

A new set of edge-conditioned basis functions is used to determine the modal characteristics of a large variety of nonstandard waveguide str uctures. Since the electromagnetic field includes the proper edge cond itions at metallic corners and since the new basis functions are readi ly Fourier transformed, a considerable reduction in computational effo rt with respect to standard modal field-matching techniques is observe d. Similar to procedures involving other known sets of applicable basi s functions, the analysis achieves a higher reliability level, as it c ompletely avoids relative convergence phenomena. The method is demonst rated at the examples of several waveguide structures, such as the L-s hape, T-shape, and cross-iris-shape waveguides; the rectangular coaxia l waveguide; and the ridged circular waveguide. Results for the cut-of f wave numbers of TE and TM modes are shown to be in excellent agreeme nt with those from standard modal field-matching techniques and previo usly published data. (C) 1998 John Wiley & Sons, Inc.