Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387415
R. Gardner
The relationship between the current in the lightning strike and the radiated fields varies considerably by both the physical assumptions used and the approximate model chosen for the lightning channel. In this paper, we consider the lightning channel in two cylindrical regions -the conducting channel and the region outside the channel. Most of the lightning literature uses various departures from a transmission-line model to predict the current evolution. We use the two region plasma model in the frequency domain and estimate the radial field distribution with solutions to Bessel's equation and solve for the propagation constant in the usual way. We find that the high frequency components of the current in the channel are attenuated as they propagate upward implying that the high frequency fields are generated from currents near the surface.
{"title":"Propagation Along a Cylindrical Model of the Lightning Return Stroke","authors":"R. Gardner","doi":"10.1109/ICEAA.2007.4387415","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387415","url":null,"abstract":"The relationship between the current in the lightning strike and the radiated fields varies considerably by both the physical assumptions used and the approximate model chosen for the lightning channel. In this paper, we consider the lightning channel in two cylindrical regions -the conducting channel and the region outside the channel. Most of the lightning literature uses various departures from a transmission-line model to predict the current evolution. We use the two region plasma model in the frequency domain and estimate the radial field distribution with solutions to Bessel's equation and solve for the propagation constant in the usual way. We find that the high frequency components of the current in the channel are attenuated as they propagate upward implying that the high frequency fields are generated from currents near the surface.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123796316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387426
V. de la Rubia, J. Zapata
A further exploitation of a matrix-valued transfer function describing electromagnetic behaviour is considered in this work. In addition to the inclusion of modal ports is the analysis domain, new computational domain ports are taken into account. What it is aimed for with this new port definition is to allow FEM analysis even though some boundary field distributions are not yet established, in other words, to be able to carry out the full-wave analysis in a given structure in spite of certain physical shapes and dimensions not yet being established; and afterwards, to make it possible to cause field discontinuities (continuities) with ease to consider conducting strips (slots) in the computational domain.
{"title":"Rapid Finite-Element Parameter Space Sweep for Microwave Devices","authors":"V. de la Rubia, J. Zapata","doi":"10.1109/ICEAA.2007.4387426","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387426","url":null,"abstract":"A further exploitation of a matrix-valued transfer function describing electromagnetic behaviour is considered in this work. In addition to the inclusion of modal ports is the analysis domain, new computational domain ports are taken into account. What it is aimed for with this new port definition is to allow FEM analysis even though some boundary field distributions are not yet established, in other words, to be able to carry out the full-wave analysis in a given structure in spite of certain physical shapes and dimensions not yet being established; and afterwards, to make it possible to cause field discontinuities (continuities) with ease to consider conducting strips (slots) in the computational domain.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124936287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387417
V. Dehghanian, M. Okhowat, M. Hakkak
A novel bi-linear planar near-field antenna measurement technique is presented as a superior alternative to other planar near-field measurement techniques. It is shown that the planar far-field can be precisely predicted by measuring the near-field samples just along two intersecting lines instead of undergoing the time taking process of scanning the whole near-field plane. This makes Bi-linear technique a very fast, accurate, and timely efficient near-field measurement method. Through the simulations and theoretical analysis, the advantages and disadvantages of this new technique are discussed and results so far demonstrate its superiority over other planar near-field techniques.
{"title":"A Novel Bi-linear Technique for Planar Near-Field Antenna Measurement Applications","authors":"V. Dehghanian, M. Okhowat, M. Hakkak","doi":"10.1109/ICEAA.2007.4387417","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387417","url":null,"abstract":"A novel bi-linear planar near-field antenna measurement technique is presented as a superior alternative to other planar near-field measurement techniques. It is shown that the planar far-field can be precisely predicted by measuring the near-field samples just along two intersecting lines instead of undergoing the time taking process of scanning the whole near-field plane. This makes Bi-linear technique a very fast, accurate, and timely efficient near-field measurement method. Through the simulations and theoretical analysis, the advantages and disadvantages of this new technique are discussed and results so far demonstrate its superiority over other planar near-field techniques.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124979156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387342
G. Addamo, R. Orta, R. Tascone, G. Virone, O. Peverini
Leaky coaxial cables (LCX) are used as distributed radiators for indoor communications. This kind of structure suffers of low antenna efficiency and not uniform radiated field along the cable length. In this paper a design technique in order to overcome both these problem is presented.
{"title":"Design of uniformly radiating slotted coaxial cables","authors":"G. Addamo, R. Orta, R. Tascone, G. Virone, O. Peverini","doi":"10.1109/ICEAA.2007.4387342","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387342","url":null,"abstract":"Leaky coaxial cables (LCX) are used as distributed radiators for indoor communications. This kind of structure suffers of low antenna efficiency and not uniform radiated field along the cable length. In this paper a design technique in order to overcome both these problem is presented.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"38 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114039821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387467
R. Adams
It has recently been demonstrated that band-limited representations of localized solution modes provide an effective basis for accurate, compressed, direct representations of plane wave scattering from finite targets. The principle limitation of this previously reported compression strategy is the computational cost to determine the required basis of localizing modes. The present paper overcomes this limitation and outlines a fast, direct procedure for computing the response of finite targets to plane wave excitations. Numerical examples are included for TMz scattering from simple targets.
{"title":"Fast Direct Compression of the Plane Wave Response Matrix","authors":"R. Adams","doi":"10.1109/ICEAA.2007.4387467","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387467","url":null,"abstract":"It has recently been demonstrated that band-limited representations of localized solution modes provide an effective basis for accurate, compressed, direct representations of plane wave scattering from finite targets. The principle limitation of this previously reported compression strategy is the computational cost to determine the required basis of localizing modes. The present paper overcomes this limitation and outlines a fast, direct procedure for computing the response of finite targets to plane wave excitations. Numerical examples are included for TMz scattering from simple targets.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"65 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114015465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387428
N. Marais, D. Davidson
This paper compares three full-wave finite element time domain (FETD) formulations. The first is based on the vector wave equation; the others on Maxwell's equations, viz. the EBHD formulation that discretises Eoarr, Boarr, Hoarr and Doarr and the EB formulation that discretises only Eoarr and Boarr. The latter two formulations use a combination of 1-form and 2-form discretisation to avoid an auxiliary mesh. A method for making the EBHD formulation operational is presented and conditions for finite difference time domain (FDTD)-like explicit operation are discussed. Numerical results for a three dimensional cavity and a coaxial transmission line show that the EBHD formulation has serious performance limitations.
{"title":"A Comparison of Some Finite Element Time Domain Formulations in Electromagnetics","authors":"N. Marais, D. Davidson","doi":"10.1109/ICEAA.2007.4387428","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387428","url":null,"abstract":"This paper compares three full-wave finite element time domain (FETD) formulations. The first is based on the vector wave equation; the others on Maxwell's equations, viz. the EBHD formulation that discretises Eoarr, Boarr, Hoarr and Doarr and the EB formulation that discretises only Eoarr and Boarr. The latter two formulations use a combination of 1-form and 2-form discretisation to avoid an auxiliary mesh. A method for making the EBHD formulation operational is presented and conditions for finite difference time domain (FDTD)-like explicit operation are discussed. Numerical results for a three dimensional cavity and a coaxial transmission line show that the EBHD formulation has serious performance limitations.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122833400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387378
P. Vavassori, M. Grimsditch
The experimental and theoretical aspects for obtaining the magnetic information carried by laser beams diffracted from an array of nano-sized magnetic objects is reviewed. Experimentally it will be shown that the Magneto Optic Kerr Effect (MOKE) hysteresis loops recorded on diffracted beams can be quite different from those recorded in the reflected beam. We will show that the Diffracted MOKE (D-MOKE) loops are proportional to the magnetic form factor, or equivalently, to the Fourier component of the magnetization corresponding to the reciprocal lattice vector of the diffracted beam. In conjunction with micromagnetic simulations D-MOKE provides a powerful and non-destructive technique for investigating the magnetization reversal process in submicron sized magnetic particles.
{"title":"Magnetic Information in the Light Diffracted by Submicron-scale Periodic Magnetic Arrays","authors":"P. Vavassori, M. Grimsditch","doi":"10.1109/ICEAA.2007.4387378","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387378","url":null,"abstract":"The experimental and theoretical aspects for obtaining the magnetic information carried by laser beams diffracted from an array of nano-sized magnetic objects is reviewed. Experimentally it will be shown that the Magneto Optic Kerr Effect (MOKE) hysteresis loops recorded on diffracted beams can be quite different from those recorded in the reflected beam. We will show that the Diffracted MOKE (D-MOKE) loops are proportional to the magnetic form factor, or equivalently, to the Fourier component of the magnetization corresponding to the reciprocal lattice vector of the diffracted beam. In conjunction with micromagnetic simulations D-MOKE provides a powerful and non-destructive technique for investigating the magnetization reversal process in submicron sized magnetic particles.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131104906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387432
A. V. van Deursen, L. Vandamme
Based on an exact two-dimensional current distribution we calculate the geometrical factor for conductance fluctuations. A thin square sample is assumed with four or two active electrodes. Circular electrodes of different size are considered at the sample corners.
{"title":"Schwarz-Christoffel approach for conductance fluctuations","authors":"A. V. van Deursen, L. Vandamme","doi":"10.1109/ICEAA.2007.4387432","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387432","url":null,"abstract":"Based on an exact two-dimensional current distribution we calculate the geometrical factor for conductance fluctuations. A thin square sample is assumed with four or two active electrodes. Circular electrodes of different size are considered at the sample corners.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134624558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387394
R. Remis
In this paper we present a Krylov subspace method to efficiently compute the low-frequency response of multiconductor transmission lines. Through a Lanczos-type algorithm we generate so-called spectral Lanczos decomposition approximations on an entire frequency interval of interest. Low frequencies are approximated first, since we use the inverse of the transmission line system matrix in the Lanczos algorithm. Although this inverse is not a sparse matrix, computing its action on a vector still requires an order N amount of work, where N is the total number of unknowns. Moreover, the inverse is a so-called J-symmetric matrix because of reciprocity. This property is exploited in the Lanczos algorithm and approximations are constructed via a three-term recurrence relation. The overall algorithm is therefore very efficient.
{"title":"An Efficient Krylov Subspace Method to Simulate the Low-Frequency Response of Multiconductor Transmission Lines","authors":"R. Remis","doi":"10.1109/ICEAA.2007.4387394","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387394","url":null,"abstract":"In this paper we present a Krylov subspace method to efficiently compute the low-frequency response of multiconductor transmission lines. Through a Lanczos-type algorithm we generate so-called spectral Lanczos decomposition approximations on an entire frequency interval of interest. Low frequencies are approximated first, since we use the inverse of the transmission line system matrix in the Lanczos algorithm. Although this inverse is not a sparse matrix, computing its action on a vector still requires an order N amount of work, where N is the total number of unknowns. Moreover, the inverse is a so-called J-symmetric matrix because of reciprocity. This property is exploited in the Lanczos algorithm and approximations are constructed via a three-term recurrence relation. The overall algorithm is therefore very efficient.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125376406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-21DOI: 10.1109/ICEAA.2007.4387430
O. Tuncer, C. Lu, N. Nair, B. Shanker, L. Kempel
The generalized finite element method, first introduced by Babuska, is a framework that uses a partition of unity concept to construct a higher order representation of fields within a computation domain without using tessellation or imposing constraints on the space of basis functions. A key result is that the error representing the total field in the computational domain is related to the local representation error in each patch. This implies that one may be able to choose an appropriate set of basis in each sub-domain. While a bulk of literature based on this technique has been applied to construct solvers for scalar and elliptic differential equations, only recently was a method to analyze vector electromagnetic problems proposed. The basis functions proposed in the paper satisfy the requisite boundary conditions at the interface and demonstrate the appropriate h and p convergence. In this paper, the error in wave propagation is studied via a series of numerical experiments, for different classes of local basis functions-polynomials and exponentials.
{"title":"Analysis of Error Propagation in Vector Generalized Finite Element Methods","authors":"O. Tuncer, C. Lu, N. Nair, B. Shanker, L. Kempel","doi":"10.1109/ICEAA.2007.4387430","DOIUrl":"https://doi.org/10.1109/ICEAA.2007.4387430","url":null,"abstract":"The generalized finite element method, first introduced by Babuska, is a framework that uses a partition of unity concept to construct a higher order representation of fields within a computation domain without using tessellation or imposing constraints on the space of basis functions. A key result is that the error representing the total field in the computational domain is related to the local representation error in each patch. This implies that one may be able to choose an appropriate set of basis in each sub-domain. While a bulk of literature based on this technique has been applied to construct solvers for scalar and elliptic differential equations, only recently was a method to analyze vector electromagnetic problems proposed. The basis functions proposed in the paper satisfy the requisite boundary conditions at the interface and demonstrate the appropriate h and p convergence. In this paper, the error in wave propagation is studied via a series of numerical experiments, for different classes of local basis functions-polynomials and exponentials.","PeriodicalId":273595,"journal":{"name":"2007 International Conference on Electromagnetics in Advanced Applications","volume":"148 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132017613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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