NONLINEAR INVERSION IN TE SCATTERING

A method for reconstructing the complex permittivity of a bounded inho mogeneous object from measured scattered-field data is presented. This paper extends the method previously developed for the TM case to the more complicated TE case, In the TM case, the electric-field integral equation involves an integral operator whose integrand was simply a pr oduct of the background Green's function, contrast, and field. In the TE case, the magnetic field is polarized along the axis of an inhomoge neous cylinder of arbitrary cross section and the corresponding integr al equation contains derivatives of both the background Green's functi on and the field. The nonlinear inversion based upon the modified-grad ient method as presented in the literature is applied to the magnetic- field equation, However, the integral equation can also be formulated as an electric-field integral equation for the two transversal compone nts of the electric field. Again, the integrand is a product of the ba ckground Green's function, contrast, and electric-field vector. The de rivatives are operative outside the integral. In this paper, the latte r formulation will be taken as a point of departure to develop a nonli near inversion scheme using the modified-gradient method.