A Fast Algorithm for the Analysis of Scattering by Elongated Cavities

The electromagnetic scattering from elongated, arbitrarily shaped, open-ended cavities have been studied extensively over the years. In this paper we introduce the fast encapsulating domain decomposition (EDD) scheme for the analysis of radar cross section (RCS) of such open-ended cavities. Problem definition, key principles, analysis, and implementation of the proposed solution scheme are presented in detail. The EDD advantages stem from domain decomposition along the elongated dimension and representing the fields on the cross-sections in the spectral domain, which enables us to separate the fields into in- and out-going waves. This diagonolizes the translation between the cross sections, thus reducing the per segment computational complexity from $O((N^A)^3)$ to $O(N^W(N^A)^2)$, where $N^A$ is the number of aperture unknowns and $N^W$ is the number of wall unknowns per segment, satisfying $N^W<<N^A$, since we construct the segmentation step to be small compared to the cross section. The results of the EDD are demonstrated on an S-shape elongated open-ended cavity.