Subspace-Based Distorted FDFD Iterative Method for Inverse Scattering

The distorted FDFD-based iterative method (DFIM) and subspace theory are combined to improve the efficiency of electromagnetic scattering inversion in this letter. With the help of singular value decomposition (SVD), the proposed subspace-based DFIM (S-DFIM) updates the total electric field with an increment produced by the deterministic subspace of the equivalent source. In the iterations, this increment can make the total electric field more accurate than that by the DFIM, which leads to faster convergence. In addition, a self-adapting scheme for getting the parameter of Tikhonov regularization is also proposed to improve the imaging quality. Numerical results show that the efficiency of the proposed method is greatly improved while maintaining good accuracy.