Multi-GPOF Method in the Calculation of the Rectangular Waveguide Layered Green's Functions

In this letter, we adopt a new procedure in the calculation of the layered Green's functions in the rectangular waveguide structure. In this procedure, the surface-wave poles are extracted first, and then the generalized pencil-of-function (GPOF) method is applied to approximate the spectral-domain Green's function along the real axis of the
$k_{\rho}$
plane directly. Because no branch point is introduced in this procedure, improvement can be achieved compared to the traditional discrete complex image method (DCIM). In order to make this procedure more accurate and robust in both near- and far-field regions, a specially devised multiple-times GPOF procedure is applied to approximate the spectral-domain Green's function. Numerical results in this letter demonstrate the accuracy of our method.