LAUSR

A multiregion nested equivalent source approximation (NESA) is presented for the fast analysis of electromagnetic scattering by piecewise homogeneous media. NESA was introduced for the analysis of metallic problems at low and moderate frequencies, and later extended to the fully dynamic case with the introduction of a directional scheme. In this communication, we modify the wideband scheme for the analysis of arbitrary penetrable media; the asymptotic computational costs of the algorithm are compatible with the state-of-the-art factorizations, namely, linear and quasi-linear [ $\mathcal {O}(N)$ and $\mathcal {O}(N \log N)$ ] for moderate and high-frequency problems, respectively. Numerical examples validate the accuracy and favorable computational cost of NESA when applied to penetrable bodies.