The Experts below are selected from a list of 24012 Experts worldwide ranked by ideXlab platform
Giuseppe Schettini - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic scattering of a pulsed signal by conducting Cylindrical targets embedded in a half space medium
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: Cristina Ponti, Massimo Santarsiero, Giuseppe SchettiniAbstract:The pulsed scattering by buried perfectly conducting cylinders is solved with the Cylindrical Wave approach. The source of the scattering problem is a wideband excitation from a plane-Wave source field. A spectral approach is employed, expressing the electric field as a superposition of monochromatic contribution. Time-domain response is found through the inverse Fourier transform on the spectra relevant to each field contributions. Numerical implementation of the method turns out to be very accurate. The technique has important applications in the simulation of the scenarios of embedded objects within remote sensing techniques. Results are plotted to simulate both A-scan and B-scan plots typical of ground penetrating radar measurements. The method has been validated through a comparison with a numerical technique available in the literature.
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on beam shaping of the field radiated by a line source coupled to finite or infinite photonic crystals
Journal of The Optical Society of America A-optics Image Science and Vision, 2016Co-Authors: S Ceccuzzi, Cristina Ponti, Vakhtang Jandieri, Paolo Baccarelli, Giuseppe SchettiniAbstract:Comparison of the beam-shaping effect of a field radiated by a line source, when an ideal infinite structure constituted by two photonic crystals and an actual finite one are considered, has been carried out by means of two different methods. The lattice sums technique combined with the generalized reflection matrix method is used to rigorously investigate the radiation from the infinite photonic crystals, whereas radiation from crystals composed of a finite number of rods along the layers is analyzed using the Cylindrical-Wave approach. A directive radiation is observed with the line source embedded in the structure. With an increased separation distance between the crystals, a significant edge diffraction appears that provides the main radiation mechanism in the finite layout. Suitable absorbers are implemented to reduce the above-mentioned diffraction and the reflections at the boundaries, thus obtaining good agreement between radiation patterns of a localized line source coupled to finite and infinite photonic crystals, when the number of periods of the finite structure is properly chosen.
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electromagnetic scattering by a circular cylinder buried below a slightly rough gaussian surface
Journal of The Optical Society of America A-optics Image Science and Vision, 2014Co-Authors: Muhammad Arshad Fiaz, Cristina Ponti, F Frezza, Giuseppe SchettiniAbstract:A two-dimensional beam is scattered by a cylinder buried below a slightly rough surface. The Cylindrical Wave approach is applied, i.e., Cylindrical Waves are employed as basis functions of the fields scattered by the cylinder. Moreover, a spectral representation of both the incident field and the Cylindrical Waves is used. Rough surface deviation is coped with by the first-order small perturbation method. Therefore, to a zeroth-order solution relevant to scattering in the case of a flat surface, a first-order approximation is superimposed. The theoretical approach has been implemented for a periodic surface with Gaussian roughness spectrum.
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asymptotic solution for a scattered field by Cylindrical objects buried beneath a slightly rough surface
Near Surface Geophysics, 2013Co-Authors: Muhammad Arshad Fiaz, Cristina Ponti, Fabrizio Frezza, Lara Pajewski, Giuseppe SchettiniAbstract:The problem of scattering of electromagnetic Waves from a set of Cylindrical objects buried beneath a slightly rough surface is undertaken with the Cylindrical Wave approach as a method of analysis. The small perturbation method is used to compute the scattered field from a rough surface. Numerical results for a rough surface with a sinusoidal profile are obtained with asymptotic evaluation.
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electromagnetic scattering by a metallic cylinder buried in a lossy medium with the Cylindrical Wave approach
IEEE Geoscience and Remote Sensing Letters, 2013Co-Authors: F Frezza, Cristina Ponti, Giuseppe Schettini, Lara Pajewski, Nicola TedeschiAbstract:The 2-D electromagnetic scattering of a plane Wave by a perfectly conducting cylinder buried in a lossy medium is presented. The problem of reflection and transmission of both the plane Wave and the Cylindrical Wave at the interface with a dissipative medium has been faced, taking into account the general case of inhomogeneous Waves. The scattering problem has been solved with the Cylindrical-Wave approach. The theoretical solution has been numerically implemented in a Fortran code, and the numerical results have been compared with both the literature and simulations with a commercial software.
W Wiesbeck - One of the best experts on this subject based on the ideXlab platform.
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offset Cylindrical reflector antenna fed by a parallel plate luneburg lens for automotive radar applications in millimeter Wave
IEEE Transactions on Antennas and Propagation, 2003Co-Authors: Youngjin Park, W WiesbeckAbstract:Using a single offset Cylindrical parabolic reflector and a parallel-plate Luneburg lens, a novel high-gain and high-efficiency antenna is developed for automotive radar at mm-Wave frequencies. Particularly, a pair of small corrugated extensions is added to the lens for a Cylindrical Wave. Thus, by feeding a Cylindrical Wave to the reflector, especially the performance in elevation is enhanced, keeping the complete antenna compact. For verification, a prototype antenna for an adaptive cruise control radar at 76.5 GHz is designed and measured. The theoretical results are verified with good agreement.
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offset Cylindrical reflector antenna fed by a parallel plate luneburg lens for automotive radar applications in mm Wave
IEEE Antennas and Propagation Society International Symposium, 2002Co-Authors: Youngjin Park, Alexander Herschlein, W WiesbeckAbstract:Using a single offset Cylindrical parabolic reflector and an improved parallel-plate Luneburg lens, a novel antenna is developed for automotive radar in the mm-Wave range. By adding linearly- or circularly-corrugated extensions to the parallel-plate Luneburg lens, a Cylindrical Wave illuminates the reflector, and hence good performances are achieved. Using GO, the aperture field of the antenna is found and then far-fields of the entire antenna are derived using the aperture field integration method. Design procedures of the entire antenna are presented. For verification of design rules and simulation, a prototype antenna for an adaptive cruise control (ACC) radar at 76.5 GHz is designed and measured. The antenna has properties of a relatively wide scan angle and multiple beams.
Leung Tsang - One of the best experts on this subject based on the ideXlab platform.
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full Wave simulations of scattering in vegetation for microWave remote sensing of soil moisture
International Geoscience and Remote Sensing Symposium, 2020Co-Authors: Leung Tsang, Andreas Colliander, Simon YuehAbstract:The vegetation layer effects play an important role on microWave remote sensing of soil moisture. The classical Radiative Transfer Equation (RTE) and Distorted Born Approximation (DBA) model assume that the position of scatterers in vegetation is statistically homogeneous in 3D space. Such assumptions are incorrect because the scatterers in vegetation are in clusters and also in the form of extended cylinders. In this paper, we develop a new hybrid method that makes the Numerical Maxwell Model of 3D (NMM3D) full-Wave simulation possible for vegetation. A geometry setup is introduced to account for the gap effects and vegetation structure. The T-matrix of a single plant composed of multiple cylinders in a cluster is extracted using Huygen's principle and the vector Cylindrical Wave (VCW) expansions. Foldy-Lax multiple scattering (FL) equations are used to solve for the transmissivity of the vegetation layer. The convergence and accuracy of the hybrid method are verified using Ansys High Frequency Structure Simulator (HFSS). Transmission through wheat is calculated using the hybrid method and compared with those of RTE/DBA.
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propagation of Waves in randomly distributed cylinders using three dimensional vector Cylindrical Wave expansions in foldy lax equations
IEEE Journal on Multiscale and Multiphysics Computational Techniques, 2019Co-Authors: Huanting Huang, Leung Tsang, Andreas Colliander, Simon YuehAbstract:In this article, we develop a hybrid method to calculate the propagation of microWaves in randomly distributed dielectric cylinders. The hybrid method combines off-the-shelf techniques for single object and our developed techniques of Foldy–Lax (FL) method that include extracting the T-matrix for single object, vector translation addition theorem, and solving FL multiple scattering equations. For Cylindrical scatterers such as tree trunks, the T-matrix in vector three-dimensional Cylindrical Waves are extracted from infinite cylinder approximation (ICA). In solving FL to calculate statistical moments, we iterate one order of multiple scattering at a time, with averaging over realizations performed after each order. This physically based iterative method of calculating statistical moments converges faster than the traditional iterative method of calculating the exact solution for each realization. The main purpose is to simulate tall tree trunks at the L-band and ICA is of sufficient accuracies. Numerical results are illustrated for a large number of cylinders of up to 196 and cylinder lengths of up to 94 Wavelengths, which are typical of forests at the L-band. Results of the simulations of the hybrid method show that the transmission coefficients of Waves are several times larger than that of the commonly used models of the radiative transfer equation and distorted Born approximation.
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Full Wave Solutions of Multiple Scattering Using 3D Vector Cylindrical Wave Expansions In Foldy-Lax Equations
2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, 2019Co-Authors: Huanting Huang, Leung Tsang, Kung-hau DingAbstract:In this paper, we develop a method for full Wave simulations of vegetation/forests based on the scattered field formulation of Foldy-Lax multiple scattering equation (FL). The novelty of this method is that the 3D vector Cylindrical Wave expansions are used in FL, because the trees are compactly enclosed by the infinite Cylindrical surfaces without overlap. For Cylindrical scatterers such as tree trunks, infinite cylinder approximation is used to calculate the T matrix. Vector translation addition theorem of 3D vector Cylindrical Waves is used, and the FL is solved iteratively. Solving FL is equivalent to solving Maxwell equations and all the interactions and multiple scatterings among the scatterers are considered. The correctness of the method is verified by HFSS. This method has been implemented on parallel computing for large problems such as full Wave simulations of forests.
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full Wave simulations of vegetation trees using 3d vector Cylindrical Wave expansions in foldy lax multiple scattering equations
IEEE International Conference on Computational Electromagnetics, 2019Co-Authors: Huanting Huang, Leung Tsang, Andreas Colliander, S H YuehAbstract:In this paper, we develop a method for full Wave simulations of vegetation/trees based on the scattered field formulation of Foldy-Lax multiple scattering equation (FL). The 3D vector Cylindrical Wave expansions are used because the trees are compactly enclosed by the infinite Cylindrical surfaces without overlap. For Cylindrical scatterers such as tree trunks, Infinite Cylinder Approximation is used to calculate the T matrix. Vector translation addition theorem of Cylindrical Waves is used and the FL is solved iteratively. Solving FL is equivalent to solving Maxwell equations and all the interactions and multiple scatterings among the scatterers are considered. The correctness of the method is verified by HFSS and the method is applicable for large problems such as full Wave simulations of forests.
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coupling of vias in electronic packaging and printed circuit board structures with finite ground plane
IEEE Transactions on Advanced Packaging, 2003Co-Authors: Leung Tsang, Dennis MillerAbstract:A full Wave method is presented for modeling and analyzing multiple interactions among vertical vias in densely packaged integrated circuits and printed circuit board with ground plane of finite extent. In such structures, the TEM mode in the planar structure is excited and can propagate and cause interaction of Waves among vias. Reflections will also occur at the edges of the finite ground plane. The electromagnetic analysis methodology is an extension of the previous methodology in analyzing multiple scattering among vias for infinite ground plane . The analysis is based upon the Cylindrical Wave mode expansion of the magnetic field Green's function, the Foldy-Lax multiple scattering formalism and utilizing the resonator modes of a circular cavity. The circular resonator modes are transformed into Cylindrical Waves onto the Cylindrical via structures. Numerical results illustrate the physics of the underlying resonance scattering problems. We consider the cases of a) two coupled active vias of differential mode and b) two coupled vias of common mode. Results are also illustrated for ground plane resonance and the effects of shorting vias on such resonance. The effects of off-centering and the presence of idle vias are also illustrated.
Cristina Ponti - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic scattering of a pulsed signal by conducting Cylindrical targets embedded in a half space medium
IEEE Transactions on Antennas and Propagation, 2017Co-Authors: Cristina Ponti, Massimo Santarsiero, Giuseppe SchettiniAbstract:The pulsed scattering by buried perfectly conducting cylinders is solved with the Cylindrical Wave approach. The source of the scattering problem is a wideband excitation from a plane-Wave source field. A spectral approach is employed, expressing the electric field as a superposition of monochromatic contribution. Time-domain response is found through the inverse Fourier transform on the spectra relevant to each field contributions. Numerical implementation of the method turns out to be very accurate. The technique has important applications in the simulation of the scenarios of embedded objects within remote sensing techniques. Results are plotted to simulate both A-scan and B-scan plots typical of ground penetrating radar measurements. The method has been validated through a comparison with a numerical technique available in the literature.
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on beam shaping of the field radiated by a line source coupled to finite or infinite photonic crystals
Journal of The Optical Society of America A-optics Image Science and Vision, 2016Co-Authors: S Ceccuzzi, Cristina Ponti, Vakhtang Jandieri, Paolo Baccarelli, Giuseppe SchettiniAbstract:Comparison of the beam-shaping effect of a field radiated by a line source, when an ideal infinite structure constituted by two photonic crystals and an actual finite one are considered, has been carried out by means of two different methods. The lattice sums technique combined with the generalized reflection matrix method is used to rigorously investigate the radiation from the infinite photonic crystals, whereas radiation from crystals composed of a finite number of rods along the layers is analyzed using the Cylindrical-Wave approach. A directive radiation is observed with the line source embedded in the structure. With an increased separation distance between the crystals, a significant edge diffraction appears that provides the main radiation mechanism in the finite layout. Suitable absorbers are implemented to reduce the above-mentioned diffraction and the reflections at the boundaries, thus obtaining good agreement between radiation patterns of a localized line source coupled to finite and infinite photonic crystals, when the number of periods of the finite structure is properly chosen.
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electromagnetic scattering by a circular cylinder buried below a slightly rough gaussian surface
Journal of The Optical Society of America A-optics Image Science and Vision, 2014Co-Authors: Muhammad Arshad Fiaz, Cristina Ponti, F Frezza, Giuseppe SchettiniAbstract:A two-dimensional beam is scattered by a cylinder buried below a slightly rough surface. The Cylindrical Wave approach is applied, i.e., Cylindrical Waves are employed as basis functions of the fields scattered by the cylinder. Moreover, a spectral representation of both the incident field and the Cylindrical Waves is used. Rough surface deviation is coped with by the first-order small perturbation method. Therefore, to a zeroth-order solution relevant to scattering in the case of a flat surface, a first-order approximation is superimposed. The theoretical approach has been implemented for a periodic surface with Gaussian roughness spectrum.
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asymptotic solution for a scattered field by Cylindrical objects buried beneath a slightly rough surface
Near Surface Geophysics, 2013Co-Authors: Muhammad Arshad Fiaz, Cristina Ponti, Fabrizio Frezza, Lara Pajewski, Giuseppe SchettiniAbstract:The problem of scattering of electromagnetic Waves from a set of Cylindrical objects buried beneath a slightly rough surface is undertaken with the Cylindrical Wave approach as a method of analysis. The small perturbation method is used to compute the scattered field from a rough surface. Numerical results for a rough surface with a sinusoidal profile are obtained with asymptotic evaluation.
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electromagnetic scattering by a metallic cylinder buried in a lossy medium with the Cylindrical Wave approach
IEEE Geoscience and Remote Sensing Letters, 2013Co-Authors: F Frezza, Cristina Ponti, Giuseppe Schettini, Lara Pajewski, Nicola TedeschiAbstract:The 2-D electromagnetic scattering of a plane Wave by a perfectly conducting cylinder buried in a lossy medium is presented. The problem of reflection and transmission of both the plane Wave and the Cylindrical Wave at the interface with a dissipative medium has been faced, taking into account the general case of inhomogeneous Waves. The scattering problem has been solved with the Cylindrical-Wave approach. The theoretical solution has been numerically implemented in a Fortran code, and the numerical results have been compared with both the literature and simulations with a commercial software.
Youngjin Park - One of the best experts on this subject based on the ideXlab platform.
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offset Cylindrical reflector antenna fed by a parallel plate luneburg lens for automotive radar applications in millimeter Wave
IEEE Transactions on Antennas and Propagation, 2003Co-Authors: Youngjin Park, W WiesbeckAbstract:Using a single offset Cylindrical parabolic reflector and a parallel-plate Luneburg lens, a novel high-gain and high-efficiency antenna is developed for automotive radar at mm-Wave frequencies. Particularly, a pair of small corrugated extensions is added to the lens for a Cylindrical Wave. Thus, by feeding a Cylindrical Wave to the reflector, especially the performance in elevation is enhanced, keeping the complete antenna compact. For verification, a prototype antenna for an adaptive cruise control radar at 76.5 GHz is designed and measured. The theoretical results are verified with good agreement.
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offset Cylindrical reflector antenna fed by a parallel plate luneburg lens for automotive radar applications in mm Wave
IEEE Antennas and Propagation Society International Symposium, 2002Co-Authors: Youngjin Park, Alexander Herschlein, W WiesbeckAbstract:Using a single offset Cylindrical parabolic reflector and an improved parallel-plate Luneburg lens, a novel antenna is developed for automotive radar in the mm-Wave range. By adding linearly- or circularly-corrugated extensions to the parallel-plate Luneburg lens, a Cylindrical Wave illuminates the reflector, and hence good performances are achieved. Using GO, the aperture field of the antenna is found and then far-fields of the entire antenna are derived using the aperture field integration method. Design procedures of the entire antenna are presented. For verification of design rules and simulation, a prototype antenna for an adaptive cruise control (ACC) radar at 76.5 GHz is designed and measured. The antenna has properties of a relatively wide scan angle and multiple beams.
