A diagonalized improved subspace-based optimization method for solving 2-D inverse scattering problems

This letter proposes a diagonalized improved subspace-based optimization method (DISOM) by introducing the diagonal approximation to the improved subspace-based optimization method (ISOM). In the diagonal approximation which has been used in the contrast source inversion, a diagonal operator is used to replace the nonlinear operator of full contrast inversion and relates the fields and induced currents. Due to the diagonal approximation, a more simplified objective function is obtained. Consequently, the iteration procedure is simplified and the computation time is reduced. Numerical examples demonstrate that the proposed DISOM has the capability of reconstructing not only isotropic objects but also uniaxial anisotropic objects. Furthermore, the quality of the reconstruction results obtained by DISOM is almost the same as the ones by utilizing ISOM, while DISOM saves about one fourth of the computational time.