The Debye model with multiple relaxation times is most suitable for highly accurate description of the dispersion characteristics of many media

such as biological tissues

soil

and water

among the developed empirical models.In order to reconstruct the electromagnetic properties of these dispersive media simultaneously

a modified time-domain inverse scattering technique is presented.Firstly

in the proposed technology

the nonlinearity and ill-posedness of the inverse problem is circumvented by an iterative method and the Tikhonov's regularization

respectively.Secondly

a set of closed gradients (Frchet derivatives) of its cost functional with respect to objective parameters are derived for the aforementioned inverse problem.Then

the finite-difference time-domain (FDTD) method and any conjugate gradient (CG) method is applied

at its each iteration

to solve the resulting forward and backward sub-problem

respectively.Lastly

the feasibility and robustness for the inversion technique are preliminarily confirmed by two one-dimensional (1-D) numerical examples where a model of the additive white Gaussian noise (AWGN) is considered.