The Experts below are selected from a list of 14082 Experts worldwide ranked by ideXlab platform
Magdalena Salazarpalma - One of the best experts on this subject based on the ideXlab platform.
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green s function using schelkunoff integrals for horizontal electric dipoles over an imperfect ground plane
IEEE Transactions on Antennas and Propagation, 2016Co-Authors: Walid Dyab, T K Sarkar, Mohammad N Abdallah, Magdalena SalazarpalmaAbstract:Recently, Schelkunoff integrals have been used to formulate a Green’s function for analysis of radiation from a vertical electric dipole over an imperfect ground plane. Schelkunoff integrals were proved to be more suitable for numerical computation for large radial distances than the Sommerfeld integrals which are used conventionally to deal with antennas over an imperfect ground. This is because Schelkunoff integrals have no convergence problem on the tail of the contour of integration, especially when the fields are calculated near the boundary separating the media and for large source–receiver separations. In this paper, the Schelkunoff integrals are utilized to derive a Green’s function for the case of a horizontal electric dipole radiating over an imperfect ground plane (a two-media problem where the lower medium is lossy). A detailed comparison between the presented expressions and the conventional ones based on Sommerfeld integrals is illustrated both numerically and analytically.
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a physics based green s function for analysis of vertical electric dipole radiation over an imperfect ground plane
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Walid Dyab, T K Sarkar, Magdalena SalazarpalmaAbstract:Sommerfeld integrals appear in the solution of radiation and scattering problems involving antennas in planar multi-layered media. In the conventional approach it is quite difficult to numerically integrate the tails related to Sommerfeld integrals as they are not only oscillatory but also slowly decaying. Numerous research efforts have been developed to accelerate the accurate computation of such integrals, for example, by changing the integration path in the complex plane, or by using extrapolation methods. In this paper, the physical origin of the problem of the Sommerfeld integral tails is studied. Based on the physical description of the problem, a new Green's function for the radiation of a vertical electric dipole over an imperfect ground plane is derived. The new Green's function involves what is called in this paper Schelkunoff integrals. The new formulation is compared to the conventional Sommerfeld formulation, mainly with respect to the speed of convergence when the fields are calculated near the ground plane. The characteristics of the new formulation show that if Schelkunoff integrals are used in the appropriate region, the problem of Sommerfeld integral tails, which plagued the electromagnetic community for decades, can be totally abolished.
Walid Dyab - One of the best experts on this subject based on the ideXlab platform.
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green s function using schelkunoff integrals for horizontal electric dipoles over an imperfect ground plane
IEEE Transactions on Antennas and Propagation, 2016Co-Authors: Walid Dyab, T K Sarkar, Mohammad N Abdallah, Magdalena SalazarpalmaAbstract:Recently, Schelkunoff integrals have been used to formulate a Green’s function for analysis of radiation from a vertical electric dipole over an imperfect ground plane. Schelkunoff integrals were proved to be more suitable for numerical computation for large radial distances than the Sommerfeld integrals which are used conventionally to deal with antennas over an imperfect ground. This is because Schelkunoff integrals have no convergence problem on the tail of the contour of integration, especially when the fields are calculated near the boundary separating the media and for large source–receiver separations. In this paper, the Schelkunoff integrals are utilized to derive a Green’s function for the case of a horizontal electric dipole radiating over an imperfect ground plane (a two-media problem where the lower medium is lossy). A detailed comparison between the presented expressions and the conventional ones based on Sommerfeld integrals is illustrated both numerically and analytically.
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On the relation between Surface Plasmons and Sommerfeld's Surface Electromagnetic Waves
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), 2013Co-Authors: Walid Dyab, Mohammad N Abdallah, Tapan K. Sarkar, Magdalena Salazar-palmaAbstract:The term “Surface Plasmons, SP” was first coined in the middle of the twentieth century to study the interaction of plasma oscillations with the electrons on the surface of metal foils. Surface Plasmons have a wide variety of applications such as in Terahertz spectroscopy. In the literature, Surface Plasmons are frequently related to Surface Electromagnetic Waves, SEW, which were first studied by Zenneck and independently by Sommerfeld in the early 1900's. However, Zenneck and Sommerfeld surface waves are rarely examined critically in the current literature on SP. Looking for a solid understanding for the relation between SP and SEW, it was necessary to study Sommerfeld's work thoroughly. The revisiting of Sommerfeld's work on Surface waves led to some important conclusions which are communicated in this paper.
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a physics based green s function for analysis of vertical electric dipole radiation over an imperfect ground plane
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Walid Dyab, T K Sarkar, Magdalena SalazarpalmaAbstract:Sommerfeld integrals appear in the solution of radiation and scattering problems involving antennas in planar multi-layered media. In the conventional approach it is quite difficult to numerically integrate the tails related to Sommerfeld integrals as they are not only oscillatory but also slowly decaying. Numerous research efforts have been developed to accelerate the accurate computation of such integrals, for example, by changing the integration path in the complex plane, or by using extrapolation methods. In this paper, the physical origin of the problem of the Sommerfeld integral tails is studied. Based on the physical description of the problem, a new Green's function for the radiation of a vertical electric dipole over an imperfect ground plane is derived. The new Green's function involves what is called in this paper Schelkunoff integrals. The new formulation is compared to the conventional Sommerfeld formulation, mainly with respect to the speed of convergence when the fields are calculated near the ground plane. The characteristics of the new formulation show that if Schelkunoff integrals are used in the appropriate region, the problem of Sommerfeld integral tails, which plagued the electromagnetic community for decades, can be totally abolished.
Jingfang Huang - One of the best experts on this subject based on the ideXlab platform.
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adapting free space fast multipole method for layered media green s function algorithm and analysis
Applied and Computational Harmonic Analysis, 2019Co-Authors: Min Hyung Cho, Jingfang HuangAbstract:Abstract In this paper, we present a numerical algorithm for an accurate and efficient computation of the convolution of the frequency domain layered media Green's function with a given density function. Instead of compressing the convolution matrix directly as in the classical fast multipole method, fast direct solvers, and fast H -matrix algorithms, this new algorithm considers a translated form of the original matrix so that many existing building blocks from the highly optimized free-space fast multipole method can be easily adapted to the Sommerfeld integral representations of the layered media Green's function. An asymptotic analysis is performed on the Sommerfeld integrals for large orders to provide an estimate of the decay rate in the new “multipole” and “local” expansions. To avoid the highly oscillatory integrand in the original Sommerfeld integral representations when the source and target are close to each other, or when they are both close to the interface in the scattered field, mathematically equivalent alternative direction integral representations are introduced. The convergence of the multipole and local expansions formulas and quadrature rules for the original and alternative direction integral representations are numerically validated.
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adapting free space fast multipole method for layered media green s function algorithm and analysis
arXiv: Numerical Analysis, 2019Co-Authors: Min Hyung Cho, Jingfang HuangAbstract:In this paper, we present a numerical algorithm for the accurate and efficient computation of the convolution of the frequency domain layered media Green's function with a given density function. Instead of compressing the convolution matrix directly as in the classical fast multipole method, fast direct solvers, and fast H-matrix algorithms, the new algorithm considers a translated form of the original matrix so that many existing building blocks from the highly optimized free-space fast multipole method can be easily adapted to the Sommerfeld integral representations of the layered media Green's function. An asymptotic analysis is performed on the Sommerfeld integrals for large orders to provide an estimate of the decay rate in the new "multipole" and "local" expansions. In order to avoid the highly oscillatory integrand in the original Sommerfeld integral representations when the source and target are close to each other, or when they are both close to the interface in the scattered field, mathematically equivalent alternative direction integral representations are introduced. The convergence of the multipole and local expansions and formulas and quadrature rules for the original and alternative direction integral representations are numerically validated.
Min Hyung Cho - One of the best experts on this subject based on the ideXlab platform.
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adapting free space fast multipole method for layered media green s function algorithm and analysis
Applied and Computational Harmonic Analysis, 2019Co-Authors: Min Hyung Cho, Jingfang HuangAbstract:Abstract In this paper, we present a numerical algorithm for an accurate and efficient computation of the convolution of the frequency domain layered media Green's function with a given density function. Instead of compressing the convolution matrix directly as in the classical fast multipole method, fast direct solvers, and fast H -matrix algorithms, this new algorithm considers a translated form of the original matrix so that many existing building blocks from the highly optimized free-space fast multipole method can be easily adapted to the Sommerfeld integral representations of the layered media Green's function. An asymptotic analysis is performed on the Sommerfeld integrals for large orders to provide an estimate of the decay rate in the new “multipole” and “local” expansions. To avoid the highly oscillatory integrand in the original Sommerfeld integral representations when the source and target are close to each other, or when they are both close to the interface in the scattered field, mathematically equivalent alternative direction integral representations are introduced. The convergence of the multipole and local expansions formulas and quadrature rules for the original and alternative direction integral representations are numerically validated.
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adapting free space fast multipole method for layered media green s function algorithm and analysis
arXiv: Numerical Analysis, 2019Co-Authors: Min Hyung Cho, Jingfang HuangAbstract:In this paper, we present a numerical algorithm for the accurate and efficient computation of the convolution of the frequency domain layered media Green's function with a given density function. Instead of compressing the convolution matrix directly as in the classical fast multipole method, fast direct solvers, and fast H-matrix algorithms, the new algorithm considers a translated form of the original matrix so that many existing building blocks from the highly optimized free-space fast multipole method can be easily adapted to the Sommerfeld integral representations of the layered media Green's function. An asymptotic analysis is performed on the Sommerfeld integrals for large orders to provide an estimate of the decay rate in the new "multipole" and "local" expansions. In order to avoid the highly oscillatory integrand in the original Sommerfeld integral representations when the source and target are close to each other, or when they are both close to the interface in the scattered field, mathematically equivalent alternative direction integral representations are introduced. The convergence of the multipole and local expansions and formulas and quadrature rules for the original and alternative direction integral representations are numerically validated.
George W. Hanson - One of the best experts on this subject based on the ideXlab platform.
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Dyadic Green's functions and guided surface waves for a surface conductivity model of graphene
Journal of Applied Physics, 2008Co-Authors: George W. HansonAbstract:An exact solution is obtained for the electromagnetic field due to an electric current in the presence of a surface conductivity model of graphene. The graphene is represented by an infinitesimally thin, local, and isotropic two-sided conductivity surface. The field is obtained in terms of dyadic Green’s functions represented as Sommerfeld integrals. The solution of plane wave reflection and transmission is presented, and surface wave propagation along graphene is studied via the poles of the Sommerfeld integrals. For isolated graphene characterized by complex surface conductivity = Ј + j, a proper transverse-electric surface wave exists if and only if 0 ͑associated with interband conductivity, and a proper transverse-magnetic surface wave exists for associated with intraband conductivity. By tuning the chemical potential at infrared frequencies, the sign of can be varied, allowing for some control over surface wave properties.
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dyadic green s functions and guided surface waves for a surface conductivity model of graphene
arXiv: Materials Science, 2007Co-Authors: George W. HansonAbstract:An exact solution is obtained for the electromagnetic field due to an electric current in the presence of a surface conductivity model of graphene. The graphene is represented by an infinitesimally-thin, local and isotropic two-sided conductivity surface. The field is obtained in terms of dyadic Green's functions represented as Sommerfeld integrals. The solution of plane-wave reflection and transmission is presented, and surface wave propagation along graphene is studied via the poles of the Sommerfeld integrals. For isolated graphene characterized by complex surface conductivity, a proper transverse-electric (TE) surface wave exists if and only if the imaginary part of conductivity is positive (associated with interband conductivity), and a proper transverse-magnetic (TM) surface wave exists when the imaginary part of conductivity is negative (associated with intraband conductivity). By tuning the chemical potential at infrared frequencies, the sign of the imaginary part of conductivity can be varied, allowing for some control over surface wave properties.
