FFT-Accelerated Near-Field Scattering Evaluation

An FFT-based algorithm is presented for rapidly post-processing the integral-equation based solution of scattering problems to evaluate the fields at an arbitrary number of nearby points. The proposed algorithm uses a similar approach to the adaptive integral method (AIM) but contends with the fact that the fields are not Galerkin tested with basis functions but instead point tested. It reduces the computational costs compared to the brute-force method, especially when the number of observer points is large.