Angela Dell'Aversano | Università della Campania Luigi Vanvitelli (original) (raw)

Papers by Angela Dell'Aversano

As is well known, in through-the wall imaging one needs to estimate the wall electromagnetic para... more As is well known, in through-the wall imaging one needs to estimate the wall electromagnetic parameters in order to get properly focused images. Even under the simplest case in which the wall can be assimilated as a single homogeneous slab, this problem puts some difficulties since the wall dielectric permittivity and thickness are nonlinearly linked to the reflected field data. The usual way to go on that problem is through some optimization iterative procedure which can be time consuming and can suffer from false solutions. In this contribution we propose a method that avoids the previously mentioned drawbacks by leveraging on a MIMO configuration. The main idea is to estimate the wall transmission coefficient rather than its electromagnetic properties. This way, one estimates the kernel of the relevant (for imaging) scattering operator instead of constructing it after wall parameters have been estimated. More in detail, it is shown that the characterization stage is cast as a linear inverse problem which is solved by a Truncated-Singular Value Decomposition method. The proposed method avoids optimization but in principle can be applied only for lossless walls. However, multi layered walls can be dealt with as well. In this contribution we focus only on the wall transmission coefficient estimation; once it has been obtained imaging can be achieved by standard back-propagation algorithms. In particular, the study is developed for a single wall and 3D vector case and some numerical examples are reported to check the theory.

IEEE Geoscience and Remote Sensing Letters, Dec 1, 2016

The shape reconstruction of a strong large scattering object made up of elementary shapes and emb... more The shape reconstruction of a strong large scattering object made up of elementary shapes and embedded within a large investigation domain is dealt with from the undersampled multifrequency backscattered field data. First, a migration algorithm is run that, despite aliasing, allows reducing the spatial region, where the scatterer can be located. Then, the overall shape is determined by identifying the elementary ones through a multiple signal classification algorithm. The approach is numerically tested for a 2-D geometry, and it proves to be robust against uncertainties on data.

In this contribution we briefly present the experimental verification of incoherent radar imaging... more In this contribution we briefly present the experimental verification of incoherent radar imaging approaches recently developed in the framework of medical imaging. In particular, a prototype radar system is described and breast and head phantoms are developed and employed to collect the measurements.

IEEE Access, 2019

The problem of detecting defective elements in antenna arrays from near-field measurements by a M... more The problem of detecting defective elements in antenna arrays from near-field measurements by a MUSIC method is addressed. It is shown that, owing to the rank deficiency of the involved correlation matrix, MUSIC is indeed no better than back-transformation or matrix methods. In order to restore MUSIC performance, a rank recovering procedure is required. Therefore, here, we introduce a rank recovering method which is properly tailored to address the pertinent near-field configuration. Numerical examples, obtained for 2D scalar cases and linear array antennas, show the effectiveness of the method. INDEX TERMS Array diagnostics, inverse imaging, multiple signal classification (MUSIC).

IEEE Signal Processing Magazine, Jul 1, 2014

ABSTRACT This article deals with two significant aspects related to synthetic aperture radar imag... more ABSTRACT This article deals with two significant aspects related to synthetic aperture radar imaging (SAR-I) of relevant theoretical and applicative interest. The first objective regards the analysis of the most-used SAR-I approaches under the unified mathematical framework provided by the Porter?Bojarski integral equation. The second objective is to provide an updated overview on how SAR-I research is generalizing previous algorithms to deal with unconventional scenarios.

2022 IEEE Conference on Antenna Measurements and Applications (CAMA), Dec 14, 2022

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Mar 1, 2014

ABSTRACT In GPR prospecting, strong reflections due to the background material interface can hind... more ABSTRACT In GPR prospecting, strong reflections due to the background material interface can hinder the detection of localized buried scatterers, especially when the targets are close (in terms of probing wavelength) to the interface. Moreover, signals due to objects located outside the investigated domain and occurring in the observation time window may dramatically affect the reliability of the results. In order to mitigate such kind of clutter, an entropy based approach has been recently proposed in the frame of intra-wall diagnostic. In this paper, we assess the performance of such an approach by processing experimental data collected in laboratory controlled conditions and referred for the challenging situation of shallower dielectric and metallic targets, whose back-scattered fields overlap in time with the air-soil interface signal. In addition, a performance comparison of the proposed method is performed with other two approaches, i.e., the mean subtraction method and the subspace projection procedure.

A combined Migration-MUSIC approach is adopted to deal with the inverse problem of reconstructing... more A combined Migration-MUSIC approach is adopted to deal with the inverse problem of reconstructing the shape of strong scatterers composed of elementary shapes and embedded within an electrically large investigation domain from under-sampled backscattered field data. The scatterers are deployed over a metallic plane, which mimics the ground floor, as in SAR scenarios. In order to mitigate aliasing, migration images obtained by using disjoint available frequency bands are combined in an interferometric way. Next as each elementary shape is characterized by a small amount of parameters, a MUSIC algorithm is employed to reconstruct them separately.

ABSTRACT In this paper we examine Time Reversal MUSIC (TRM) performance for two orthogonal polari... more ABSTRACT In this paper we examine Time Reversal MUSIC (TRM) performance for two orthogonal polarizations: TMz and TEz. It is shown that if a little amount of noise corrupts the data there is an intrinsic limit on the number of scatterers that can be successfully detected. This number turns out to be the so-called number of degrees of freedom of the scattered field. Moreover, it is found that Time Reversal MUSIC performance changes depending on the considered polarization.

Advanced electromagnetics, Sep 1, 2016

The problem of detecting the breath activities of a human subject is addressed. A CW signal is us... more The problem of detecting the breath activities of a human subject is addressed. A CW signal is used to probe the scene and the MUSIC algorithm is exploited to detect frequency doppler modulation introduced by chest movements. For this particular measurement configuration, the correlation matrix results rank deficient. In order to restore the rank, two decorrelation techniques are compared by exploiting numerical data.

IEEE Geoscience and Remote Sensing Letters, Jun 1, 2014

Time-reversal MUSIC is a super-resolving imaging method that allows localizing point-like scatter... more Time-reversal MUSIC is a super-resolving imaging method that allows localizing point-like scatterers with a resolution much smaller than the diffraction limits. In this letter, we check this statement for a populated scattering scene for the case of 2-D cylindrical perfect electric conducting objects. It is shown that when the data are corrupted even by a small amount of noise, there is an intrinsic limit on the number of scatterers that can be successfully detected. This number turns out to be linked with the so-called number of degrees of freedom corresponding to the spatial region where the targets are located. Moreover, it is shown that the transverse electric polarization is more sensitive to the noise as, given the size of the spatial region occupied by the scatterers, the maximum number of scatterers that can be detected is three times lower than that detectable by the transverse magnetic illumination. Index Terms-Electromagnetic inverse scattering, inverse problems, small scatterers, time-reversal MUSIC (TRM).

IEEE sensors letters, Jun 1, 2017

The problem of detecting the respiration rate of a human being located behind a wall is addressed... more The problem of detecting the respiration rate of a human being located behind a wall is addressed using a continuous wave Radar. A Toeplitz based MUSIC algorithm is employed to detect the Doppler modulation induced by chest movements. This method, unlike other smoothing procedures, allows to restore the rank of the correlation matrix without sacrificing the length of observation time interval and hence the resolution. Experimental results show that the proposed method outperforms the commonly used FFT procedure.

Rebar detection can be cast as a the problem of localizing point-like scatterers sparsely enclose... more Rebar detection can be cast as a the problem of localizing point-like scatterers sparsely enclosed within a prescribed investigation domain. Both TR-MUSIC and Compressed Sensing approaches can deal with it and are compared in this paper. The role of noise on data, data sparseness and mutual coupling are examined by numerical examples.

EGU General Assembly Conference Abstracts, May 1, 2014

Journal of Imaging, Jun 17, 2019

This paper deals with the problem of estimating the RCS from near-field data by image-based appro... more This paper deals with the problem of estimating the RCS from near-field data by image-based approaches. In particular, a rigorous focusing procedure based on a weighted adjoint scheme, which is also applicable to an arbitrary measurement curve, is developed. The developed formalism allows us to address the important question concerning the need to employ a multi-frequency configuration to estimate the RCS. Accordingly, it is shown that if RCS is required at a given frequency, then the target image obtained solely at such a frequency can be exploited provided that the spatial truncation arising from the size of the investigated area is properly taken into account.

Journal of Imaging, Feb 1, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Applied sciences, Dec 9, 2019

Imaging buried objects embedded within electrically large investigation domains can require a lar... more Imaging buried objects embedded within electrically large investigation domains can require a large number of measurement points. This is impractical if long data acquisition time cannot be tolerated or the system is conceived to work at some stand-off distance from the air/soil interface; for example, if it is mounted over some flying platform. In order to reduce the number of spatial measurements, here, we propose a method for detecting and localizing shallowly buried scattering targets from under-sampled far-field data. The method is based on a scattering model derived from the equivalence theorem for electromagnetic radiation. It exploits multi-frequency data and does not require that the transmitter and receivers are synchronized, making the source non-cooperative. To provide a benchmark against which spatial data have to be reduced, first, the number of required spatial measurements is examined by analyzing the properties of the relevant scattering operator. Then, since under-sampling data produces aliasing artifacts, frequency diversity (i.e., multi-frequency data) is exploited to mitigate those artifacts. In particular, single-frequency reconstructions are properly fused and a criterion for selecting the frequencies to be used is provided. Numerical examples show that the method allows for satisfactory target transverse localization with a number of measurements that are much less than the ones required by other methods commonly used in subsurface imaging.