An iterative procedure for combining the advantages of a multi-frequency and multi-resolution inversion algorithm

Starting from the iterative multi-scaling approach previously studied for monochromatic illuminations, two multi-resolution strategies for dealing with multi-frequency inverse scattering experiments have been developed. The first procedure is based on the integration of the iterative multi-scaling algorithm into a frequency-hopping reconstruction scheme, while in the second one the multi-frequency data are simultaneously processed exploiting a multi-resolution expansion of the problem unknowns. The numerical and the experimental analysis presented in this contribution concern with a preliminary assessment of the reconstruction effectiveness of the proposed approaches in comparison with a monochromatic multi-step process.