Circulant Adaptive Integral Method (CAIM) for Electromagnetic Scattering From Large Targets of Arbitrary Shape

A novel version of the 2-D adaptive integral method (AIM), called circulant AIM, is presented. The method is suited particularly to cylindrical structures of a quasicircular cross section, such as the wall of a jet engine inlet. Unlike in standard AIM, the auxiliary grid, where the scatterer is embedded, is no longer Cartesian, but polar/cylindrical, resembling a spider´s web. In this way, a much lower number of auxiliary unknowns are required, since only delta sources sufficiently close to the outer surface are utilized. Apart from significant savings in memory, the main advantage of this geometry is that the resulting Green´s function matrix is not merely Toeplitz, but also circulant, leading to enhanced efficiency of the technique.