The CG-FFT algorithm for inversion [EM inverse scattering applications]

Electromagnetic inverse scattering is very important for a number of sensing and remote sensing applications. However, since the inverse scattering problem is ill-posed, a large number of iterations are required when using the conjugate gradient (CG) scheme. In this work, we investigate an efficient method to speed up the linear inverse scattering with the aid of the fast Fourier transform (FFT). We discuss how to perform 2D FFT in the CG method for the inverse-scattering problem and compare the computational complexity between the usual CG method and the CG-FFT method. Finally, reconstruction results are given, which show that the proposed algorithm can be used to solve large-scale inverse problems efficiently.