“…In this context, the Singularity Expansion Method (SEM), initially proposed by Baum in 1971 [1], states that the electromagnetic Complex Natural Resonances (CNRs) of an object can be calculated from the backscattered late time response in the time domain [2,3]. This has been used in the evaluation of geological formations, buried objects, and other radar operations, for example [4,5]. In Equation (1), which is the starting SEM time-domain equation, the signal y(t) is decomposed in complex residues R i and poles s i = α i + jω i , each with a damping factor and a complex frequency.…”