Improving Efficiency in Computing EM Fields Excited in a Finite-Length Cylindrical Cavity by a Longitudinal Aperture

An updated formulation for the electromagnetic fields produced in a finite-length circular cylindrical cavity by plane wave excitation of a thin longitudinal aperture is provided. The update replaces a triple summation over mode indices m, n, and l with a double summation over m and n using a previously shown analytical contour-integration method. A key question in the method is how to represent the quality factor $(Q_{mnl})$ in the summation since the index l has been eliminated; two approaches are investigated for this step. Results demonstrate similar accuracy for the two approaches but different properties in terms of the frequency responses obtained.