A new methodology based on an iterative multiscaling for microwave imaging

In this paper, the problem of the localization, shaping, and dielectric permittivity reconstruction of dielectric targets is addressed. The scatterers under test are inhomogeneous cylinders of arbitrary cross sections probed by a set of incident electromagnetic fields of TM type. The scattered field data are processed in order to locate and roughly recover the objects´ shapes. The scatterers under test are then reconstructed with an increasing accuracy by means of an iterative multiscaling procedure until stationary reconstructions are achieved. The proposed method is presented jointly with a modified conjugate-gradient inversion procedure in order to minimize the rising cost function. However, this methodology is independent from the minimization algorithm, and other and more efficient algorithms can be used. In order to assess the effectiveness of the iterative multiscaling method, the results of several test cases (with and without noise) are presented and discussed in more detail.