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.