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Giuseppe Schettini - One of the best experts on this subject based on the ideXlab platform.
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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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Cylindrical wave approach for the electromagnetic scattering problem by buried two dimensional objects
International Workshop on Advanced Ground Penetrating Radar, 2009Co-Authors: Lara Pajewski, Giuseppe Schettini, F FrezzaAbstract:A spectral-domain method, for the solution of the two-dimensional electromagnetic plane-wave scattering by a finite set of perfectly-conducting or dielectric cylinders buried in a dielectric half-space, has been developed. The scattered field is represented in terms of a superposition of Cylindrical Waves, and use is made of the plane-wave spectrum to take into account the reflection and transmission of such Waves by the interface. The problem is solved for both the near- and the far-field regions, for TM and TE polarizations. In this work we briefly resume the theoretical basis of our approach. For configurations in which more obstacles are buried in the ground, and they are near to one another, we give details about the convergence rate of our method, and about the properties of our algorithms for the integration of Cylindrical functions. With our technique it is possible to simulate two-dimensional buried obstacles of general shape, by means of a suitable set of circular-section cylinders: in this paper we show preliminary results of simulations carried out using arrays of same-radius circular cylinders, and of different-radius circular cylinders.
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plane wave expansion of Cylindrical functions in lossy media
Optics Communications, 2006Co-Authors: F Frezza, Lara Pajewski, D Saccoccioni, Giuseppe SchettiniAbstract:Cylindrical Waves, expressed as the product of a Hankel function of integer order times a sinusoidal angular factor, are often employed in the solution of two-dimensional scattering problems. In this paper, a general closed-form expression for the angular spectrum of a Cylindrical wave in a lossy medium is derived.
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comments on scattering by a finite set of perfectly conducting cylinders buried in a dielectric half space a spectral domain solution
IEEE Transactions on Antennas and Propagation, 2005Co-Authors: M Di Vico, F Frezza, Lara Pajewski, Giuseppe SchettiniAbstract:An analytical-numerical technique, for the solution of the two-dimensional electromagnetic plane-wave scattering by a finite set of perfectly conducting circular cylinders buried in a dielectric half-space, is presented. The problem is solved for both the near- and the far-field regions, for TM and TE polarizations. The diffracted field is represented in terms of a superposition of Cylindrical Waves and use is made of the plane-wave spectrum to take into account the reflection and transmission of such Waves by the interface. The validity of the approach is confirmed by comparisons with results available in the literature, with very good agreement. The multiple interactions between two buried cylinders have been studied by considering both the induced currents and the scattered field diagrams. Applications of the method to objects of arbitrary cross-section simulated by a suitable configuration of circular cylinders are shown.
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numerical study of the reflection of Cylindrical Waves of arbitrary order by a generic planar interface
Journal of Electromagnetic Waves and Applications, 1999Co-Authors: Riccardo Borghi, Giuseppe Schettini, F Frezza, C Santini, Massimo SantarsieroAbstract:Cylindrical Waves are fundamental building blocks in constructing the solution of two-dimensional scattering problems. The reflection problem of a Cylindrical wave of any integer order from a generic plane surface of discontinuity for the electromagnetic constants is faced making use of the plane-wave decomposition approach. The resulting numerical problem, involving the quadrature of highly oscillating functions is solved by means of suitable techniques. Numerical results are presented for some cases of practical interest. A comparison with a particular case for which a closed-form solution is available is also presented.
Leung Tsang - One of the best experts on this subject based on the ideXlab platform.
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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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signal integrity analysis of package and printed circuit board with multiple vias in substrate of layered dielectrics
IEEE Transactions on Advanced Packaging, 2010Co-Authors: Boping Wu, Leung TsangAbstract:This paper successfully extends the Foldy-Lax multiple scattering approach to model massively-coupled multiple vias in substrate of layered dielectrics between two horizontal power/ ground plates. The dyadic Green's functions of layered dielectrics are expressed in vector Cylindrical Waves and modal representations. Formulations are derived for admittances and S-parameters of single via and multiple vias structures. The CPUs and results of S-parameters are illustrated for various sizes of via array. For the case of 16 × 16 via array through hybrid dielectrics in single interior layer, the CPU is about 0.8 s per frequency and is at least three orders of magnitude faster than Ansoft HFSS. The results are within 5% difference of accuracy up to 20 GHz. This full-wave method is able to include all the coupling effects among the multiple vias. It is also shown that the approach of using effective dielectric constant by assuming an effective homogeneous media does not give accurate results.
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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.
F Frezza - One of the best experts on this subject based on the ideXlab platform.
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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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Cylindrical wave approach for the electromagnetic scattering problem by buried two dimensional objects
International Workshop on Advanced Ground Penetrating Radar, 2009Co-Authors: Lara Pajewski, Giuseppe Schettini, F FrezzaAbstract:A spectral-domain method, for the solution of the two-dimensional electromagnetic plane-wave scattering by a finite set of perfectly-conducting or dielectric cylinders buried in a dielectric half-space, has been developed. The scattered field is represented in terms of a superposition of Cylindrical Waves, and use is made of the plane-wave spectrum to take into account the reflection and transmission of such Waves by the interface. The problem is solved for both the near- and the far-field regions, for TM and TE polarizations. In this work we briefly resume the theoretical basis of our approach. For configurations in which more obstacles are buried in the ground, and they are near to one another, we give details about the convergence rate of our method, and about the properties of our algorithms for the integration of Cylindrical functions. With our technique it is possible to simulate two-dimensional buried obstacles of general shape, by means of a suitable set of circular-section cylinders: in this paper we show preliminary results of simulations carried out using arrays of same-radius circular cylinders, and of different-radius circular cylinders.
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plane wave expansion of Cylindrical functions in lossy media
Optics Communications, 2006Co-Authors: F Frezza, Lara Pajewski, D Saccoccioni, Giuseppe SchettiniAbstract:Cylindrical Waves, expressed as the product of a Hankel function of integer order times a sinusoidal angular factor, are often employed in the solution of two-dimensional scattering problems. In this paper, a general closed-form expression for the angular spectrum of a Cylindrical wave in a lossy medium is derived.
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comments on scattering by a finite set of perfectly conducting cylinders buried in a dielectric half space a spectral domain solution
IEEE Transactions on Antennas and Propagation, 2005Co-Authors: M Di Vico, F Frezza, Lara Pajewski, Giuseppe SchettiniAbstract:An analytical-numerical technique, for the solution of the two-dimensional electromagnetic plane-wave scattering by a finite set of perfectly conducting circular cylinders buried in a dielectric half-space, is presented. The problem is solved for both the near- and the far-field regions, for TM and TE polarizations. The diffracted field is represented in terms of a superposition of Cylindrical Waves and use is made of the plane-wave spectrum to take into account the reflection and transmission of such Waves by the interface. The validity of the approach is confirmed by comparisons with results available in the literature, with very good agreement. The multiple interactions between two buried cylinders have been studied by considering both the induced currents and the scattered field diagrams. Applications of the method to objects of arbitrary cross-section simulated by a suitable configuration of circular cylinders are shown.
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numerical study of the reflection of Cylindrical Waves of arbitrary order by a generic planar interface
Journal of Electromagnetic Waves and Applications, 1999Co-Authors: Riccardo Borghi, Giuseppe Schettini, F Frezza, C Santini, Massimo SantarsieroAbstract:Cylindrical Waves are fundamental building blocks in constructing the solution of two-dimensional scattering problems. The reflection problem of a Cylindrical wave of any integer order from a generic plane surface of discontinuity for the electromagnetic constants is faced making use of the plane-wave decomposition approach. The resulting numerical problem, involving the quadrature of highly oscillating functions is solved by means of suitable techniques. Numerical results are presented for some cases of practical interest. A comparison with a particular case for which a closed-form solution is available is also presented.
Dennis G Hall - One of the best experts on this subject based on the ideXlab platform.
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circularly symmetric distributed feedback laser coupled mode treatment of te vector fields
IEEE Journal of Quantum Electronics, 1992Co-Authors: T Erdogan, Dennis G HallAbstract:The vector orientation of transverse electric (TE) fields in deriving coupled mode equations for radially outward- and inward-going modes in a circular waveguide diffraction grating is treated. The equations are derived for Cylindrical Waves in a system that is translationally invariant along the cylinder axis; the derivation is then extended to the waveguide geometry. The coupled mode equations are used to describe the operation of the circularly symmetric distributed feedback (DFB) laser. While predicting a similar dependence of the laser threshold gain on an azimuthal mode order to that found by a simpler, scalar-field treatment, the vector-field treatment predicts a fundamental difference in the location of the cavity resonances. The circular DFB laser is expected to lase in multiple azimuthal modes but maintain a relatively narrow overall spectral width. >
Anders E Bostrom - One of the best experts on this subject based on the ideXlab platform.
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the influence of pore fluid in the soil on ground vibrations from a tunnel embedded in a layered half space
Journal of Sound and Vibration, 2018Co-Authors: Zonghao Yuan, Anders E BostromAbstract:Abstract A computationally efficient semi-analytical solution for ground-borne vibrations from underground railways is proposed and used to investigate the influence of hydraulic boundary conditions at the scattering surfaces and the moving ground water table on ground vibrations. The arrangement of a dry soil layer with varying thickness resting on a saturated poroelastic half-space, which includes a circular tunnel subject to a harmonic load at the tunnel invert, creates the scenario of a moving water table for research purposes in this paper. The tunnel is modelled as a hollow cylinder, which is made of viscoelastic material and buried in the half-space below the ground water table. The wave field in the dry soil layer consists of up-going and down-going Waves while the wave field in the tunnel wall consists of outgoing and regular Cylindrical Waves. The complete solution for the saturated half-space with a Cylindrical hole is composed of down-going plane Waves and outgoing Cylindrical Waves. By adopting traction-free boundary conditions on the ground surface and continuity conditions at the interfaces of the two soil layers and of the tunnel and the surrounding soil, a set of algebraic equations can be obtained and solved in the transformed domain. Numerical results show that the moving ground water table can cause an uncertainty of up to 20 dB for surface vibrations.
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ultrasonic scattering by a side drilled hole
International Journal of Solids and Structures, 2003Co-Authors: Anders E Bostrom, Peter BovikAbstract:The scattering of elastic Waves by a side-drilled hole (sdh) i.e. a circular Cylindrical cavity, is considered. The scattering of plane or Cylindrical Waves by an sdh is an old subject; here the T matrix solution is adopted. The elastic Waves are excited by an ultrasonic probe and a model of such a probe is thus used. The Waves from the probes are expressed as a Fourier transform, i.e. as a superposition of plane Waves. These plane Waves are then transformed to the Cylindrical system centred at the sdh. To obtain the signal in a receiving ultrasonic probe an electromechanical reciprocity relation is used. The signal response is obtained as a double wavenumber integral and an azimuthal summation. In the far field the integrals can be calculated approximately by the stationary phase approximation. Some numerical examples are given, in particular concentrating on when this approximation is valid.
