Sampling method using prefiltered band-limited Green´s functions for the solution of electromagnetic integral equations

In the context of far-field scattering, the spatial spectrum of fields or currents on a scatterer may be approximated as band-limited. On this premise one can greatly simplify the computation of radiation integrals by eliminating in advance those spectral components of the Green´s function not expected to be present in the fields. This approach enables one to dispense with the notion of basis functions and, instead, represent fields and currents as well as the impedance matrix representing the Green´s function entirely in terms of a sparse set of samples, thereby obviating the need for integration. Moreover, by taking full advantage of the band-limited character of the solution, this sampling theoretical approach yields an efficient representation with a minimal number of degrees of freedom. The method was explored for scattering from two-dimensional perfect electric conductors including ellipsoidal cylinders and flat strips, in both polarizations, using uniform as well as nonuniform sampling, and yielded surprisingly good results