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postgraduate thesis: Numerical methodologies for electromagnetic parasitic system modeling and simulation
Title  Numerical methodologies for electromagnetic parasitic system modeling and simulation 

Authors  
Advisors  
Issue Date  2014 
Publisher  The University of Hong Kong (Pokfulam, Hong Kong) 
Citation  Li, P. [李平]. (2014). Numerical methodologies for electromagnetic parasitic system modeling and simulation. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5295525 
Abstract  In this thesis, to efficiently and accurately model the electromagnetic radiations from electronic and antenna systems, and to analyze the hybrid electromagnetic (EM)circuit system and the interactions between EM waves and multiphysics systems, a plethora of fullwave approaches are developed. Specifically, a set of frequencydomain methods are proposed in the first part of this thesis to characterize the electromagnetic radiations from device under test (DUT) based on the sampled nearfield data. For the first approach, the dyadic Green function (DGF) in the presence of perfectly conducting sphere is expanded by spherical vector wave functions, which is mathematically rigorous. Based on this DGF and the reciprocity theorem, the radiation outside the spherical sampling surface can be accurately predicted with only the tangential components of the electric nearfield over this sampling surface.
Sometimes for situations where electronic devices are placed in good conductive shielding enclosures with apertures or ventilation slots, only partially planar electric nearfield sampling over the apertures or the slots is sufficient according to Schelkunoff’s principle. Due to the unavailability of analytical DGF and the prohibitively computational cost for the numerical DGF, a novel twostep process approach by considering the radiation problem as a scattering issue with incident waves from the equivalent magnetic currents derived from the sampled electric nearfield is proposed.
However, the very nearfield radiation inside the sampling surface cannot be retrieved with the above two approaches. To overcome this limitation, the equivalent source reconstruction based methods are introduced by replacing the radiators with equivalent current sources that are capable of reproducing the original radiation. Due to the difficulty of acquiring the phase information of the nearfield data, a fully new iterative phaseless source reconstruction method (SRM) which only needs the amplitude of the electric field is developed. To reduce the computational cost of traditional SRM for broadband radiators, a wideband SRM based on a StoerBulirsh (SB) recursive tabular algorithm is proposed. Enhanced by an adaptive frequency sampling strategy, only a very small number of frequency samples are required.
With the purpose to capture the nonlinear response of EMcircuit systems, transient scattering from penetrable objects, surface plasmon polarization (SPP) of grapheme below the terahertz range, and the impacts of random parameters on the physical behavior of stochastic systems, various novel discontinuous Galerkin timedomain (DGTD) based methods and their extensions are developed. For a practical electronic system, apart from the EM part, the presence of lumped elements must be considered. Therefore, a hybrid EMcircuit solver is indispensable. For the EM subsystem governed by Maxwell’s equations, it is solved by DGTD with an explicit timemarching scheme. For the lumped subsystem, circuit equations are constructed based on either the modified nodal analysis (MNA) derived from Kirchoff’s current law or the basic IV relations. By introducing a port voltage and current, the EM and circuit solvers are synchronized in the temporal sequence at the lumped port. This synchronized EMcircuit solver is free of instabilities even though nonlinear circuit elements are involved.
For openregion scattering problem analysis, a novel approach by integrating the timedomain boundary integral (TDBI) algorithm with DGTD is developed. At the truncation boundary, the fields required for the incoming flux in DGTD is calculated using the TDBI from the equivalent currents over a Huygens’ surface enclosing the scatterer. The hybrid DGTDBI ensures that the radiation condition is mathematically exact and the resulting computation domain is as small as possible since the truncation boundary conforms to scatterer’s shape.
By considering the one atomthick graphene as an infinitesimally thin conductive sheet, a surface impedance boundary condition (SIBC) augmented DGTD algorithm is developed to model the graphene. With this SIBC, straightforward volumetric discretization is avoided, thus significantly reducing the memory cost and meanwhile alleviating the restriction on the minimum time marching size. Due to the complex relation between the surface conductivity σg (comprising contributions from both intraband and interband) and the angular frequency ω, direct mapping the numerical flux from the frequency to the timedomain via inverse Fourier transform is not available. To address this issue, a fastrelaxing vectorfitting (FRVF) technique is used to approximate the σg by rational functions in the Laplacedomain. Via inverse Laplace transform, the timedomain matrix equations are obtained in integral forms of time t. Resorting to finite integral technique (FIT), a fullydiscrete matrix system can be achieved.
Finally, to consider the impact of random parameters on realistic electronic systems, a stochastic solver based on DGTD and sparsegrid collocation method is developed. To reduce the number of supporting, an adaptive strategy is utilized by using the local hierarchical surplus as error indicator. To improve the flexibility of the proposed algorithm, both piecewise linear and Lagrange polynomial basis functions are employed to handle different stochastic systems. Particularly, the piecewise linear basis function is more efficient for nonsmoothly observables while Lagrange polynomials are more suitable for smoothly observables. With these strategies, the singularities and quick variations can be efficiently captured but with very small number of collocation points.
The above proposed algorithms are demonstrated by various examples, the accuracy, efficiency, and robustness of these algorithms are clearly observed. 
Degree  Doctor of Philosophy 
Subject  Electromagnetic waves  Mathematical models 
Dept/Program  Electrical and Electronic Engineering 
Persistent Identifier  http://hdl.handle.net/10722/202361 
HKU Library Item ID  b5295525 
DC Field  Value  Language 

dc.contributor.advisor  Jiang, L   
dc.contributor.advisor  Chew, WC   
dc.contributor.author  Li, Ping   
dc.contributor.author  李平   
dc.date.accessioned  20140918T02:28:14Z   
dc.date.available  20140918T02:28:14Z   
dc.date.issued  2014   
dc.identifier.citation  Li, P. [李平]. (2014). Numerical methodologies for electromagnetic parasitic system modeling and simulation. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5295525   
dc.identifier.uri  http://hdl.handle.net/10722/202361   
dc.description.abstract  In this thesis, to efficiently and accurately model the electromagnetic radiations from electronic and antenna systems, and to analyze the hybrid electromagnetic (EM)circuit system and the interactions between EM waves and multiphysics systems, a plethora of fullwave approaches are developed. Specifically, a set of frequencydomain methods are proposed in the first part of this thesis to characterize the electromagnetic radiations from device under test (DUT) based on the sampled nearfield data. For the first approach, the dyadic Green function (DGF) in the presence of perfectly conducting sphere is expanded by spherical vector wave functions, which is mathematically rigorous. Based on this DGF and the reciprocity theorem, the radiation outside the spherical sampling surface can be accurately predicted with only the tangential components of the electric nearfield over this sampling surface. Sometimes for situations where electronic devices are placed in good conductive shielding enclosures with apertures or ventilation slots, only partially planar electric nearfield sampling over the apertures or the slots is sufficient according to Schelkunoff’s principle. Due to the unavailability of analytical DGF and the prohibitively computational cost for the numerical DGF, a novel twostep process approach by considering the radiation problem as a scattering issue with incident waves from the equivalent magnetic currents derived from the sampled electric nearfield is proposed. However, the very nearfield radiation inside the sampling surface cannot be retrieved with the above two approaches. To overcome this limitation, the equivalent source reconstruction based methods are introduced by replacing the radiators with equivalent current sources that are capable of reproducing the original radiation. Due to the difficulty of acquiring the phase information of the nearfield data, a fully new iterative phaseless source reconstruction method (SRM) which only needs the amplitude of the electric field is developed. To reduce the computational cost of traditional SRM for broadband radiators, a wideband SRM based on a StoerBulirsh (SB) recursive tabular algorithm is proposed. Enhanced by an adaptive frequency sampling strategy, only a very small number of frequency samples are required. With the purpose to capture the nonlinear response of EMcircuit systems, transient scattering from penetrable objects, surface plasmon polarization (SPP) of grapheme below the terahertz range, and the impacts of random parameters on the physical behavior of stochastic systems, various novel discontinuous Galerkin timedomain (DGTD) based methods and their extensions are developed. For a practical electronic system, apart from the EM part, the presence of lumped elements must be considered. Therefore, a hybrid EMcircuit solver is indispensable. For the EM subsystem governed by Maxwell’s equations, it is solved by DGTD with an explicit timemarching scheme. For the lumped subsystem, circuit equations are constructed based on either the modified nodal analysis (MNA) derived from Kirchoff’s current law or the basic IV relations. By introducing a port voltage and current, the EM and circuit solvers are synchronized in the temporal sequence at the lumped port. This synchronized EMcircuit solver is free of instabilities even though nonlinear circuit elements are involved. For openregion scattering problem analysis, a novel approach by integrating the timedomain boundary integral (TDBI) algorithm with DGTD is developed. At the truncation boundary, the fields required for the incoming flux in DGTD is calculated using the TDBI from the equivalent currents over a Huygens’ surface enclosing the scatterer. The hybrid DGTDBI ensures that the radiation condition is mathematically exact and the resulting computation domain is as small as possible since the truncation boundary conforms to scatterer’s shape. By considering the one atomthick graphene as an infinitesimally thin conductive sheet, a surface impedance boundary condition (SIBC) augmented DGTD algorithm is developed to model the graphene. With this SIBC, straightforward volumetric discretization is avoided, thus significantly reducing the memory cost and meanwhile alleviating the restriction on the minimum time marching size. Due to the complex relation between the surface conductivity σg (comprising contributions from both intraband and interband) and the angular frequency ω, direct mapping the numerical flux from the frequency to the timedomain via inverse Fourier transform is not available. To address this issue, a fastrelaxing vectorfitting (FRVF) technique is used to approximate the σg by rational functions in the Laplacedomain. Via inverse Laplace transform, the timedomain matrix equations are obtained in integral forms of time t. Resorting to finite integral technique (FIT), a fullydiscrete matrix system can be achieved. Finally, to consider the impact of random parameters on realistic electronic systems, a stochastic solver based on DGTD and sparsegrid collocation method is developed. To reduce the number of supporting, an adaptive strategy is utilized by using the local hierarchical surplus as error indicator. To improve the flexibility of the proposed algorithm, both piecewise linear and Lagrange polynomial basis functions are employed to handle different stochastic systems. Particularly, the piecewise linear basis function is more efficient for nonsmoothly observables while Lagrange polynomials are more suitable for smoothly observables. With these strategies, the singularities and quick variations can be efficiently captured but with very small number of collocation points. The above proposed algorithms are demonstrated by various examples, the accuracy, efficiency, and robustness of these algorithms are clearly observed.   
dc.language  eng   
dc.publisher  The University of Hong Kong (Pokfulam, Hong Kong)   
dc.relation.ispartof  HKU Theses Online (HKUTO)   
dc.rights  Creative Commons: AttributionNonCommerical 3.0 Hong Kong License   
dc.rights  The author retains all proprietary rights, (such as patent rights) and the right to use in future works.   
dc.subject.lcsh  Electromagnetic waves  Mathematical models   
dc.title  Numerical methodologies for electromagnetic parasitic system modeling and simulation   
dc.type  PG_Thesis   
dc.identifier.hkul  b5295525   
dc.description.thesisname  Doctor of Philosophy   
dc.description.thesislevel  Doctoral   
dc.description.thesisdiscipline  Electrical and Electronic Engineering   
dc.description.nature  published_or_final_version   
dc.identifier.doi  10.5353/th_b5295525   