LAUSR

The electromagnetic inverse scattering problems (ISPs) have counted severe multiple scattering effects, especially those for strong scatterers (the ones with high contrasts and/or electrically large dimensions). Iterative inversion methods based on the model of the Lippmann–Schwinger integral equation (LSIE) usually fail to reconstruct such highly nonlinear ISPs. In this article, in virtue of a new recently established contraction integral equation for inversion (CIE-I), we propose a Fourier bases-expansion with CIE-I (FBE-CIE-I) inversion method to handle highly nonlinear ISPs via the contrast source inversion (CSI) scheme. In the FBE-CIE-I, the unknown contrast source is spanned within the Fourier bases, and the multi-round optimization scheme is adopted by choosing the proper number of low-frequency components; not only the model of CIE-I can be stabilized well but also the computational cost can be further reduced compared with the traditional CSI. Besides, compared with the previous inversion method based on LSIE, the resolvability and robustness of the FBE-CIE-I could be significantly enhanced in handling highly nonlinear ISPs. Numerical and experimental tests verify the interests and efficiency of the proposed method.