Electromagnetic Inverse Scattering of Axially Moving Cylindrical Targets

Abstract

Electromagnetic inverse scattering techniques are considered to reconstruct the permittivity and the velocity profiles of axially moving cylindrical targets. Two approaches are proposed. One of these is based on a two-step procedure. It is shown that it provides good approximations of the profiles to be reconstructed in a very efficient way, when the peak velocity is small with respect to the speed of light in vacuum. These features are obtained by neglecting the movement in the first step, which is devoted to the reconstruction of the geometric and dielectric properties of the cylindrical targets. The second approach is more classical and is defined as a global optimization problem. It is shown that the two procedures are in some way complementary in the sense that, when the two-step procedure can be applied, it is by far the best, with the general procedure giving large errors; vice versa, the two-step procedure is in trouble when the other one gives good results. In carrying out this analysis, some estimates on the effects of the movement on the scattered field components are deduced in the limit as the peak velocity goes to zero.Index Terms-Bianisotropic media, inverse scattering procedures, moving media, reconstruction of permittivity and velocity profiles, time-harmonic electromagnetic scattering.

Modelling Scattering of Electromagnetic Waves in Layered Media: An Up-to-Date Perspective

“…In addition, they can be used in the validation phase of inversion procedures. Just as an example, in [117] a two-step inversion procedure for detecting the dielectric permittivity and the velocity of multilayer axially moving targets has been developed, with particular emphasis to cylinders with elliptical cross sections, for which related Green's function has been deduced in [118].…”

Reconstruction of non-constant velocity profiles in pneumatic pipelines by microwave inverse scattering techniques

“…Microwave attenuation, resonance, or the Doppler effect can be used and are widely applied to the reconstructions of interest [1]. However, very few studies so far have investigated the capabilities of microwave inverse scattering techniques when moving media are involved [2].…”

“…In particular, we exploit the inverse algorithm proposed in [2], which was shown to have promising features when the axial speed values involved are much smaller than the speed of light in vacuum. Such a constraint on the axial speed is not a problem for the applications of interest.…”

“…The reconstruction process proposed in [2] is split into two parts: the first one deals with the reconstruction of the permittivity only while the second exploits the results achieved in the first part and addresses the reconstruction of the velocity profile only [2]. This algorithm was tested in [2] considering cases which could be managed by semianalytical forward solvers, like the ones involving a multilayer elliptic cylinder moving in the axial direction.…”

“…This algorithm was tested in [2] considering cases which could be managed by semianalytical forward solvers, like the ones involving a multilayer elliptic cylinder moving in the axial direction. The motion should take place in such a way that any layer has its own constant speed [3].…”