Practical considerations for the evaluation of the 3-D Green's function in a rectangular cavity moment method at high frequency

Two recently introduced methods for selecting the Ewald splitting parameter used in the evaluation of the rectangular cavity Greens's function have been tested for electro-magnetically large, lossy cavities. The input impedance of dipole radiators placed in large, lossy cavities were found using the cavity Green's function moment method. Cavities with dimensions up to 132 wavelengths have been modeled. Tests show that a splitting method optimized for the spatial arguments of the Green's functions is more efficient than a splitting based only on frequency when the Green's function three-dimensional series is evaluated individually for each set of spatial arguments. However, best efficiency is achieved when the 3-D series is evaluated with the contributions of all spatial arguments combined. Frequency based splitting is slightly more efficient in this case since a single splitting is not optimal for all spatial arguments simultaneously.