Improvement in calculation of some surface integrals: application to junction characterization in cavity filter design

A rigorous method which makes it possible to reduce a surface integral to a contour integral is developed. The application of this formulation to the study of a circular-to-rectangular waveguide junction reduces the time of computation of the scattering parameters by more than 50%. The method is used to calculate the electromagnetic coupling of circular cavities by a rectangular iris. This approach, together with an optimization procedure, has allowed the direct design of a filter without any further mechanical adjustments. The results obtained are in good agreement with experimental data.<>