Abstract
An effective way to solve the inverse scattering from dielectric objects relies on the Born approximation, which allows to linearize the problem and retrieve a qualitative reconstruction of the targets in terms of location and extent. The limits of the validity of the linear model can be extended by considering a quadratic approximation of the operator relating the scattered field data to the unknown object function. The use of the quadratic operator allows on the one hand to recover additional spatial variations of the object profile and on the other hand to mitigate the local minima (false solution) problem typically affecting nonlinear inversion methods. In this letter, we present an experimental validation of the quadratic inverse model for dielectric objects in free space. The data processing confirms that the tomographic images based on the quadratic model are better resolved compared to the ones provided by the inversion of the linear Born model.
Highlights
R ADIO Frequency (RF) tomography is a diagnostic method aiming to image targets in a scene from the electromagnetic fields scattered by them under the illumination of known incident fields [1]–[3]
RF tomography falls within the area of electromagnetic inverse scattering [8]
The focusing performance of linear and quadratic models look similar for M = N = 4
Summary
R ADIO Frequency (RF) tomography is a diagnostic method aiming to image targets in a scene from the electromagnetic fields scattered by them under the illumination of known incident fields [1]–[3]. This letter extends the previous analysis to near-zone measurement configurations providing experimental evidence of the imaging improvement offered by the quadratic model in the case of realistic targets. This analysis has not been reported to date and complements preliminary numerical authors’ studies [26]
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