On the application of the line incremental PO Green's function for the prediction of the field scattered from large bodies

The problem of computing the physical optics (PO) field scattered by a large surface is affected by numerical difficulties due to the fast oscillation of the integrand. The increase in computation time as the surface dimension grows in terms of the wavelength becomes unacceptable, especially for multiple bounce PO (e.g., for multi-reflector antenna system, beam waveguides, etc.). By using the finite element technique, the exact surface is approximated by many flat facets and the scattered field is provided by the sum of the individual field contributions. When using this technique in conjunction with a fast algorithm for evaluating the single facet contribution, the advantage may become relevant. The paper verifies the applicability of this concept using the incremental length PO Green's function (ILPOGF).