Analysis of scattering of composite cylinder structure using multilevel fast inhomogeneous plane wave algorithm

Scattering of composite cylinder structures containing both conductor and dielectric material plays an important role in the analysis of the radar cross sections (RCS) of complex targets. A fast algorithm, namely the multilevel fast inhomogeneous plane wave algorithm (MLFIPWA) (Bin Hu et al., Radio Science, vol.34, no.4, p.759-72, 1999) is implemented to solve this problem. It is based on the volume-surface integral equation (VSIE). Traditionally, the integral equation is discretized by MoM, and O(N²) computational complexity is needed when an iterative method, such as conjugate gradient (CG), is used. The fast multipole method (FMM) (Lu, C.C. and Chew, W.C., IEE Proc.-H, vol.140, no.6, 1993) is applied to accelerate the matrix-vector multiplication, and achieves O(N³2/). The FIPWA, based on a different expansion of Green´s function compared to FMM, is also proposed for this purpose, and it achieves O(N⁴3/); both attain O(NlogN) if a multilevel strategy is applied. Compared to MLFMM, the MLFIPWA can be easily expanded to solve the scattering of targets in an inhomogeneous environment. The method is accurate and efficient.