An iteration-free approach to the scattering from large objects by using incremental diffraction-type basis functions

The integral equation (IE) approach combined with the method of the moment (MoM) discretization scheme is widely used in the prediction of the electromagnetic scattering from a large complex objects. An alternative route is taken in a family of methods that employ an "iteration free" approach, where standard (e.g. RWG) basis functions are aggregated into larger functions. This notably includes the synthetic function expansion (SFX) and the characteristic basis function (CBF) methods. These aggregate basis functions are defined from the solution of smaller-size numerically-tractable problems, and then used in the MoM solution of the large problem. This allows one to incorporate the intermediate and macro-scale features of the structure, while maintaining a reduced number of unknowns. Thousand of wavelength structures can be treated with memory and CPU cost provided by a standard personal computer. Within this scheme, we proposed here a method to treat large portion of perfectly metallic planar objects containing edges. This appears a quite useful complement to the general framework of the iteration free methods.