  The computationally-efficient solution of fully non-linear microwave inverse
scattering problems (ISPs) is addressed. An innovative System-by-Design (SbD)
based method is proposed to enable, for the first time to the best of the
authors knowledge, an effective, robust, and time-efficient exploitation of an
evolutionary algorithm (EA) to perform the global minimization of the
data-mismatch cost function. According to the SbD paradigm as suitably applied
to ISPs, the proposed approach founds on (i) a smart re-formulation of the ISP
based on the definition of a minimum-dimensionality and representative set of
degrees-of-freedom (DoFs) and on (ii) the artificial-intelligence (AI)-driven
integration of a customized global search technique with a digital twin (DT)
predictor based on the Gaussian Process (GP) theory. Representative numerical
and experimental results are provided to assess the effectiveness and the
efficiency of the proposed approach also in comparison with competitive
state-of-the-art inversion techniques.
