Cleaning the distortions of an unknown image due to an unknown spatially invariant point spread f... more Cleaning the distortions of an unknown image due to an unknown spatially invariant point spread function (PSF) is a problem of particular interest for optical systems, like telescopes, wherein the radiation from the object passes trough a medium in turbulent motion. The aim of this paper is to present a stable method, based on the approach presented in [1] for the case of coherent radiation, which is able to estimate both the optical path disturbance (OPD) and the unknown object from noisy and incoherent multiple images, in absence of a reference source. The presented technique, at variance of other existing methods, [2-3], is able to take explicitly into account the measurement errors and noise without requiring any hypothesis on their statistical nature. The stability of the method is ensured by exploiting both a physical constraint on the OPD and a stabilizing functional.
IEEE Transactions on Antennas and Propagation, 2011
The synthesis of electrically large, aperiodic planar arrays with equi-amplitude excitations play... more The synthesis of electrically large, aperiodic planar arrays with equi-amplitude excitations plays an increasingly rele- vant role in satellite applications. Unfortunately, for such a kind of synthesis problems, local optimization procedures may be ineffec- tive, whereas global optimization procedures involve a severe com- putational effort. To circumvent these problems, a new determin- istic approach for fast design of aperiodic concentric
2009 3rd European Conference on Antennas and Propagation, Mar 23, 2009
The efficient analysis of large printed planar arrays with elements of arbitrary shapes and locat... more The efficient analysis of large printed planar arrays with elements of arbitrary shapes and locations is a challenging complex problem, as it requires large memory storage and long computational times. Therefore different techniques are being developed in order to reduce this cost. Aim of this paper is to determine the minimum number of unknowns required to get a given accuracy, i. e., the problem size. To this end, we exploit the concept of degrees of freedom of the radiated field and the well-known representations of the stratified Green's functions. The obtained results can provide the basis for the development of computationally effective methods for the analysis of such kind of structures.
ABSTRACT The use of microwaves is currently investigated as a tool for biomedical imaging applica... more ABSTRACT The use of microwaves is currently investigated as a tool for biomedical imaging applications, among which non-invasive diagnosis and monitoring of brain strokes. This communication aims at investigating the possibility of exploiting microwaves to follow up ischemic strokes and hence use this technology in a cooperative way with existing techniques currently used for brain stroke diagnosis. In particular, we discuss the choice of the imaging approach, the role of a priori information on the brain structure, as well as the effects on the imaging capabilities due to inaccurate positioning of the measurement probes.
IEEE Transactions on Antennas and Propagation, 2013
ABSTRACT A rigorous deterministic approach is proposed for the mask-constrained power pattern syn... more ABSTRACT A rigorous deterministic approach is proposed for the mask-constrained power pattern synthesis of shaped beams through one-dimensional sparse arrays having uniform-amplitude excitations (and variable phases). The approach includes the well known density taper procedure as a special case. The corresponding technique, which exploits an analytical formulation of the problem and convex programming routines, results in fast computation and is able to achieve optimal solutions without recurring to any global optimization. Numerical results assessing the capabilities of the proposed design method are provided, opening the way to the development of an effective approach for the synthesis of circularly symmetric shaped beams via uniformly-excited circular ring arrays.
In its Study of High Frequency Diffraction from Non-perfectly Conducting Surfaces te p 29-40 (SEE N76-20934 11-70, Jul 1, 1975
The properties of a function first introduced by Maliuzhinetz, which is relevant to the study of ... more The properties of a function first introduced by Maliuzhinetz, which is relevant to the study of scattering from a half plane with boundary condition of the impedance type, are exploited in some detail. Numerical tables and graphs are presented for the function in the range which is relevant to diffraction problems. This should be useful for analysis of scattering from complex lossy structures.
This paper describes the extension to the circular scanning case of a recently proposed approach ... more This paper describes the extension to the circular scanning case of a recently proposed approach to source/scatterers localisation problem from field data. The method is based on the concepts of Point Source Spectral Content and Local Spectral Content that allows the determination of the number and the location of a set of sources/scatterers without requiring the solution of full inverse problem, i.e., the inversion of the radiation or scatterer operator. The numerical analysis shows that the achievable performance are often better than those obtained with a rectilinear scanning.
2005 IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications
A new approach to find the electromagnetic field distribution on the ground from airplane surveys... more A new approach to find the electromagnetic field distribution on the ground from airplane surveys is proposed. The method exploits a temporal and spatial incoherent electromagnetic model of the radiation and an on board array antenna made of few elements. By solving a regularized ill-posed inverse problem, the technique allows the estimation of the on the ground intensity scene, taking explicitly into account the noise and the measurement errors due to the aircraft deviation from the nominal flight path and attitude of flight.
Geoscience and Remote Sensing IEEE International Symposium, 1998
A “bilinear” approach for the solution of the ill posed problem of subsurface imaging by ground p... more A “bilinear” approach for the solution of the ill posed problem of subsurface imaging by ground penetrating radar is proposed and discussed. A numerical validation showing the usefulness of the technique is also reported
IEEE Antennas and Propagation Society International Symposium. Transmitting Waves of Progress to the Next Millennium. 2000 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.00CH37118), 2000
With reference to the 2-D scalar problems new tools are proposed that allows one to determine the... more With reference to the 2-D scalar problems new tools are proposed that allows one to determine the “degree of non-linearity” in scattering problems while contemporary changing maximum value, dimensions, spatial frequency and shape of the unknown permittivity. The proposed tools allow identification of useful guidelines for the solution of both forward and inverse problems, and suggest a new solution strategy
ABSTRACT We present some outcomes of recent research activities concerning the optimal synthesis ... more ABSTRACT We present some outcomes of recent research activities concerning the optimal synthesis of antennas for satellite multibeam telecommunications. Recent advances include an enhancement of performances in the power synthesis of continuous aperture sources and the introduction of a new architecture for high-gain isophoric direct radiating arrays.
2006 IEEE Antennas and Propagation Society International Symposium, 2006
The aim of this paper is to present an integrated photonic TTD phaser (TPH) for PA, based on the ... more The aim of this paper is to present an integrated photonic TTD phaser (TPH) for PA, based on the technology introduced in J.E. Fouquet, (2000). In particular, the design of a digital 3 Bit TPH, feeding a 4 elements optical time steered antenna (OTSA), focusing the attention on the TPH insertion loss (IL), compactness and amplitude uniformity of the excitation coefficients distributions (AU). It is worth noting that, thanks to the modularity of the TTD unit (TTDU), TPHs able to drive larger antennas with a better beam pointing resolution can be obtained
Cleaning the distortions of an unknown image due to an unknown spatially invariant point spread f... more Cleaning the distortions of an unknown image due to an unknown spatially invariant point spread function (PSF) is a problem of particular interest for optical systems, like telescopes, wherein the radiation from the object passes trough a medium in turbulent motion. The aim of this paper is to present a stable method, based on the approach presented in [1] for the case of coherent radiation, which is able to estimate both the optical path disturbance (OPD) and the unknown object from noisy and incoherent multiple images, in absence of a reference source. The presented technique, at variance of other existing methods, [2-3], is able to take explicitly into account the measurement errors and noise without requiring any hypothesis on their statistical nature. The stability of the method is ensured by exploiting both a physical constraint on the OPD and a stabilizing functional.
IEEE Transactions on Antennas and Propagation, 2011
The synthesis of electrically large, aperiodic planar arrays with equi-amplitude excitations play... more The synthesis of electrically large, aperiodic planar arrays with equi-amplitude excitations plays an increasingly rele- vant role in satellite applications. Unfortunately, for such a kind of synthesis problems, local optimization procedures may be ineffec- tive, whereas global optimization procedures involve a severe com- putational effort. To circumvent these problems, a new determin- istic approach for fast design of aperiodic concentric
2009 3rd European Conference on Antennas and Propagation, Mar 23, 2009
The efficient analysis of large printed planar arrays with elements of arbitrary shapes and locat... more The efficient analysis of large printed planar arrays with elements of arbitrary shapes and locations is a challenging complex problem, as it requires large memory storage and long computational times. Therefore different techniques are being developed in order to reduce this cost. Aim of this paper is to determine the minimum number of unknowns required to get a given accuracy, i. e., the problem size. To this end, we exploit the concept of degrees of freedom of the radiated field and the well-known representations of the stratified Green's functions. The obtained results can provide the basis for the development of computationally effective methods for the analysis of such kind of structures.
ABSTRACT The use of microwaves is currently investigated as a tool for biomedical imaging applica... more ABSTRACT The use of microwaves is currently investigated as a tool for biomedical imaging applications, among which non-invasive diagnosis and monitoring of brain strokes. This communication aims at investigating the possibility of exploiting microwaves to follow up ischemic strokes and hence use this technology in a cooperative way with existing techniques currently used for brain stroke diagnosis. In particular, we discuss the choice of the imaging approach, the role of a priori information on the brain structure, as well as the effects on the imaging capabilities due to inaccurate positioning of the measurement probes.
IEEE Transactions on Antennas and Propagation, 2013
ABSTRACT A rigorous deterministic approach is proposed for the mask-constrained power pattern syn... more ABSTRACT A rigorous deterministic approach is proposed for the mask-constrained power pattern synthesis of shaped beams through one-dimensional sparse arrays having uniform-amplitude excitations (and variable phases). The approach includes the well known density taper procedure as a special case. The corresponding technique, which exploits an analytical formulation of the problem and convex programming routines, results in fast computation and is able to achieve optimal solutions without recurring to any global optimization. Numerical results assessing the capabilities of the proposed design method are provided, opening the way to the development of an effective approach for the synthesis of circularly symmetric shaped beams via uniformly-excited circular ring arrays.
In its Study of High Frequency Diffraction from Non-perfectly Conducting Surfaces te p 29-40 (SEE N76-20934 11-70, Jul 1, 1975
The properties of a function first introduced by Maliuzhinetz, which is relevant to the study of ... more The properties of a function first introduced by Maliuzhinetz, which is relevant to the study of scattering from a half plane with boundary condition of the impedance type, are exploited in some detail. Numerical tables and graphs are presented for the function in the range which is relevant to diffraction problems. This should be useful for analysis of scattering from complex lossy structures.
This paper describes the extension to the circular scanning case of a recently proposed approach ... more This paper describes the extension to the circular scanning case of a recently proposed approach to source/scatterers localisation problem from field data. The method is based on the concepts of Point Source Spectral Content and Local Spectral Content that allows the determination of the number and the location of a set of sources/scatterers without requiring the solution of full inverse problem, i.e., the inversion of the radiation or scatterer operator. The numerical analysis shows that the achievable performance are often better than those obtained with a rectilinear scanning.
2005 IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications
A new approach to find the electromagnetic field distribution on the ground from airplane surveys... more A new approach to find the electromagnetic field distribution on the ground from airplane surveys is proposed. The method exploits a temporal and spatial incoherent electromagnetic model of the radiation and an on board array antenna made of few elements. By solving a regularized ill-posed inverse problem, the technique allows the estimation of the on the ground intensity scene, taking explicitly into account the noise and the measurement errors due to the aircraft deviation from the nominal flight path and attitude of flight.
Geoscience and Remote Sensing IEEE International Symposium, 1998
A “bilinear” approach for the solution of the ill posed problem of subsurface imaging by ground p... more A “bilinear” approach for the solution of the ill posed problem of subsurface imaging by ground penetrating radar is proposed and discussed. A numerical validation showing the usefulness of the technique is also reported
IEEE Antennas and Propagation Society International Symposium. Transmitting Waves of Progress to the Next Millennium. 2000 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.00CH37118), 2000
With reference to the 2-D scalar problems new tools are proposed that allows one to determine the... more With reference to the 2-D scalar problems new tools are proposed that allows one to determine the “degree of non-linearity” in scattering problems while contemporary changing maximum value, dimensions, spatial frequency and shape of the unknown permittivity. The proposed tools allow identification of useful guidelines for the solution of both forward and inverse problems, and suggest a new solution strategy
ABSTRACT We present some outcomes of recent research activities concerning the optimal synthesis ... more ABSTRACT We present some outcomes of recent research activities concerning the optimal synthesis of antennas for satellite multibeam telecommunications. Recent advances include an enhancement of performances in the power synthesis of continuous aperture sources and the introduction of a new architecture for high-gain isophoric direct radiating arrays.
2006 IEEE Antennas and Propagation Society International Symposium, 2006
The aim of this paper is to present an integrated photonic TTD phaser (TPH) for PA, based on the ... more The aim of this paper is to present an integrated photonic TTD phaser (TPH) for PA, based on the technology introduced in J.E. Fouquet, (2000). In particular, the design of a digital 3 Bit TPH, feeding a 4 elements optical time steered antenna (OTSA), focusing the attention on the TPH insertion loss (IL), compactness and amplitude uniformity of the excitation coefficients distributions (AU). It is worth noting that, thanks to the modularity of the TTD unit (TTDU), TPHs able to drive larger antennas with a better beam pointing resolution can be obtained
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