Comparison of the Performance of Two Diagonal Approximations in the Framework of SOM

In this paper, a diagonal approximation is combined with subspace-based optimization method (SOM) for solving inverse scattering problems. For better understanding, the proposed method is abbreviated as DSOM-I. The diagonal approximation approximates the nonlinear operator as a diagonal one to construct a simplified cost function and the computational cost of the inversion is decreased. To evaluate the performance of the proposed method, the comparison between the proposed method and another similar method, which is abbreviated as DSOM-II, is presented. Compared with DSOM-II, DSOM-I has a more simplified cost function and less computational cost. Numerical examples demonstrate the effectiveness and efficiency of the proposed method. In addition, compared with SOM and DSOM-II, DSOM-I converges faster and has less computational loads. However, the quality of reconstruction results of SOM and DSOM-I is better than the results obtained by DSOM-I.