Coupling onto Wires Enclosed in Cavities with Apertures

This paper presents a hybrid numerical method for the electromagnetic field coupling into apertures residing on the surface of rectangular cavities. The cavity may enclose wires and cables that are typically modeled via transmission line approaches. Coupling into the cavity is analyzed via the moment method along with the cavity Green’s function to find the aperture fields whereas Pocklington’s integral equation is adapted for the wire/cable currents. The combined wire and aperture integral equation system can be solved directly or by decomposing it into the aperture and wire subsystems. The latter decomposition leads to a two-step or a multistep iterative approach for the solution of the aperture and wire currents. Of importance in this analysis is the use of acceleration algorithm for improving the convergence of the modal Green’s function series after the application of the moment method. Issues associated with the large condition of the matrix systems near cavity resonances are also addressed.