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fast and Accurate Calculation of Electromagnetic Scattering/Radiation Fields

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2019年第11期67卷 7168-7173页

作者： Liu, Yan-Nan Song, Wei Wu, Di Pan, Xiao-Min Sheng, Xin-Qing Beijing Inst Technol Sch Informat & Elect Ctr Electromagnet Simulat Beijing 100081 Peoples R China CAEP Software Ctr High Performance Numer Simulat Beijing 100088 Peoples R China Inst Appl Phys & Computat Math Beijing 100088 Peoples R China

A novel and general method for a fast calculation of scattering/radiation fields is proposed by expressing the source-field relationship through the method of moments (MoM). The scattering fields in the observation region are expanded by a set of SWGs defined on an auxiliary mesh. The associated expansion coefficients are obtained from matrix vector multiplication (MVM) of the impedance matrix in the MoM and the equivalent currents. The proposed method can enable an accurate near-field calculation without a special treatment of the singularity. Numerical experiments on targets with complex configurations are conducted to validate the performance of the proposed method.

关键词： Method of moments Surface impedance Impedance Testing Sparse matrices Electromagnetic scattering Method of moments (MoM) multilevel fast multipole algorithm near-field calculation skeletonization

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Volume integral equation equivalence principle algorithm domain decomposition with body of revolution equivalence surface

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IET MICROWAVES ANTENNAS & PROPAGATION 2018年第3期12卷 375-379页

作者： Li, Mengmeng Zhuang, Tao Chen, Rushan Nanjing Univ Sci & Technol Dept Commun Engn Nanjing Jiangsu Peoples R China

A novel equivalence principle algorithm (EPA) domain decomposition method previously for the surface integral equation is explored for volume integral equation in this work. The whole object is decomposed into several subdomains, the equivalence spheres are automatically produced to enclose each subdomain. The Rao-Wilton-Glisson (RWG) and body of revolution (BoR) basis functions are defined on the equivalence sphere surface. The equivalence currents defined on the RWG basis functions are evaluated with multilevel fast multipole algorithm, and then the currents defined on the RWGs can be projected onto the BoR basis functions. Compared with surface integral equation EPA-BoR algorithm, the ratio of the number of average original unknowns in each subdomain with respect to the equivalence unknowns is relatively larger, which leads to significant reduction of computations. Numerical simulations validate the accuracy and efficiency of the proposed method.

关键词： integral equations decomposition equivalence classes numerical analysis volume integral equation equivalence principle algorithm domain decomposition method Rao-Wilton-Glisson method RWG method body of revolution basis function BoR basis function equivalence sphere surface multilevel fast multipole algorithm surface integral equation EPA-BoR algorithm numerical simulation

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Homogenization of Microwave Metamaterial Structures Using Full-Wave Solutions and Genetic algorithms 18

Homogenization of Microwave Metamaterial Structures Using Fu...

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18th Mediterranean Microwave Symposium (MMS)

作者： Ibili, Hande Karaosmanoglu, Bariscan Ergul, Ozgur Middle East Tech Univ Dept Elect & Elect Engn Ankara Turkey

ISBN: (纸本)9781538671320

Metamaterials involve small details that create challenges in their numerical analysis. As commonly practiced, homogenization of such complex structures may simplify and facilitate their numerical solutions. However, homogenization should be performed carefully to avoid excessive modeling errors, especially for finite structures. In this paper, we present accurate homogenization of three-dimensional metamaterials involving split-ring resonators (SRRs). Electromagnetic characteristics of finite SRR structures are found by rigorous optimization via genetic algorithms, while necessary numerical simulations are accurately performed by using the multilevel fast multipole algorithm. The results demonstrate the promising effectiveness of the approach for realistic metamaterial structures.

关键词： Metamaterials electromagnetic homogenization genetic algorithms split-ring resonators multilevel fast multipole algorithm

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A Broadband Electromagnetic Solver Based on Multiscale MLFMA and Hybrid Integral Equations 18

A Broadband Electromagnetic Solver Based on Multiscale MLFMA...

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18th Mediterranean Microwave Symposium (MMS)

作者： Karaosmanoglu, Bariscan Tonga, Muhammed Ergul, Ozgur Middle East Tech Univ Dept Elect & Elect Engn Ankara Turkey

ISBN: (纸本)9781538671320

We present a fully broadband solver for fast and accurate solutions of multiscale electromagnetic problems involving both coarse and fine details. The implementation is based on a multiscale multilevel fast multipole algorithm that employs low-frequency and high-frequency expansions at suitable levels of incomplete tree structures. In addition, hybrid integral equations are used to properly formulate scattering and radiation problems in the frequency domain. Numerical results demonstrate the superior accuracy, efficiency, and stability of the implementation when solving challenging problems that cannot be handled via traditional methods.

关键词： Multiscale problems broadband solvers surface integral equations multilevel fast multipole algorithm

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IMPLEMENTATION OF THE EQUIVALENCE PRINCIPLE algorithm FOR POTENTIAL INTEGRAL EQUATIONS

IMPLEMENTATION OF THE EQUIVALENCE PRINCIPLE ALGORITHM FOR PO...

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作者： ALI FARSHKARAN MIDDLE EAST TECHNICAL UNIVERSITY

学位级别：硕士

In this thesis, a domain decomposition method based on the Huygens' principle for integral equations is studied. Step-by-step development of equivalence principle al- gorithm (EPA) is described for solving arbitrary shaped perfect electric conductor (PEC) and penetrable objects. The main advantage of EPA is its efficiency thanks to the enhanced conditioning hence accelerated iterative solutions of the matrix equa- tions derived from discretizations. For further enhancing the efficiency, the multilevel fast multipole algorithm (MLFMA) is used to speed up the matrix-vector multiplica- tions (MVMs) in EPA. Following standard implementations, a novel implementation of EPA using potential integral equations (PIEs) is further presented. EPA is general- ized to be compatible with PIEs used to formulate inner problems inside equivalence surfaces. Based on the stability of PIEs at low frequencies, the resulting EPA-PIE im- plementation is suitable for low-frequency problems involving dense discretizations with respect to wavelength. Along with the formulation and demonstration of the EPA-PIE scheme, high accuracy and stability of the implementation are presented on canonical problems.

关键词： Surface Integral Equations Equivalence Principle algorithm multilevel fast multipole algorithm Potential Formulations

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Efficient matrix filling of multilevel simply sparse method via multilevel fast multipole algorithm

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RADIO SCIENCE 2011年第5期46卷 [np]页

作者： Jiang, Zhaoneng Xu, Yuan Chen, Ru-shan Fan, Zhenhong Ding, Dazhi Nanjing Univ Sci & Technol Dept Commun Engn Nanjing 210094 Jiangsu Peoples R China

In this paper, an improved multilevel simply sparse method (MLSSM) is proposed for solving electromagnetic scattering problems that are formulated using the electric field integral equation approach. Previously, the matrix filling procedure of the conventional MLSSM is based on the adaptive cross approximation (ACA) method. Although the ACA is more efficient than direct filling, it requires a longer filling time for the far-field matrix than that of the multilevel fast multipole algorithm (MLFMA). Three problems with moderate electrical sizes are used to demonstrate that the far-field matrix filling memory of the ACA is also higher than that of the MLFMA. Hence, the MLFMA is utilized to reduce both the far-field matrix filling time and memory of the conventional MLSSM. Since the MLSSM recompresses the far-field interaction matrix of the MLFMA, the matrix-vector multiplication of the proposed method is more efficient than that of the MLFMA. Numerical results are presented to demonstrate the accuracy and efficiency of the proposed method.

关键词： electromagnetic scattering multilevel fast multipole algorithm multilevel simply sparse method

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Improved hybrid FEM/MOM combining MLFMA for composite electromagnetic scattering

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ELECTROMAGNETICS 2017年第8期37卷 513-529页

作者： Sun, Hua Long Tong, Chuang Ming Peng, Peng Air Force Engn Univ Air & Missile Def Coll Xian 710051 Shaanxi Peoples R China

A generalized hybrid scheme combining finite element method (FEM) and the method of moments (MOM) is first presented to investigate scattering from a 3-D dielectric object above a 2-D dielectric rough surface. The hybrid FEM/MOM scheme is divided into the FEM region for the object based on Helmholtz's equation and the MOM region for the rough surface based on coupled integral function, which can greatly reduce the computed region. With the rough surface getting larger, the unknowns of the rough surface get more. So MLFMA is employed to reduce computation complexity of MOM region itself and coupling interaction matrices between MOM region and FEM region. Consequently, the iterative process can be greatly accelerated. This generalized hybrid FEM/MOM is very suitable for investigating scattering from composite model of a complex material object and electrically large dielectric rough surface. Some examples verify this generalized hybrid FEM/MOM in high efficiency, low storage requirement, high precision and generality.

关键词： Composite electromagnetic scattering multilevel fast multipole algorithm method of moments rough surface

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Computational Design of Optical Couplers for Bended Nanowire Transmission Lines

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APPLIED COMPUTATIONAL ELECTROMAGNETICS SOCIETY JOURNAL 2017年第7期32卷 562-568页

作者： Tuncyurek, Yunus Emre Karaosmanoglu, Bariscan Ergul, Ozgur Middle East Tech Univ Dept Elect & Elect Engn Ankara Turkey

We present computational analysis, optimization, and design of optical couplers that can be useful to improve the transmission along bended nanowires. After demonstrating the deteriorated energy transmission due to sharp bends, which lead to out-of-phase nanowires and diffraction, we use a rigorous simulation environment to design efficient couplers made of spherical particles. For this purpose, an optimization module based on genetic algorithms is combined with the multilevel fast multipole algorithm, leading to a full-wave environment for precise designs of couplers. Numerical examples involving silver nanowires are presented to demonstrate the effectiveness of the optimization mechanism.

关键词： Genetic algorithms multilevel fast multipole algorithm nanowires optical couplers surface integral equations

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On the Use of Continuity Condition in the fast Solution of Volume-Surface Integral Equation

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IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 2017年 16卷 625-628页

作者： He, Mang Liu, Jinbo Wang, Binbin Zhang, Chuanfang Sun, Houjun Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China

The validity of the use of continuity condition (CC) is studied when it is combined with the volume-surface integral equation (VSIE) to solve the electromagnetic scattering/radiation of composite conductor-dielectric objects. It is found that the explicit enforcement of CC in VSIE may be inaccurate if the involved conductor is infinitesimally thin, but it works well for the composite structures that only contain conductors with closed surfaces. Anew combined field integral equation-volume integral equation with enforced CC (CC-CFIE-VIE) is then proposed, and a convenient way to embed it into the context of the multilevel fast multipole algorithm is also provided. Numerical results show that CC-CFIE-VIE not only reduces the overall memory usage and the CPU time of a single iteration, but also decreases the number of iterations to reach desired accuracy.

关键词： Continuity condition (CC) method of moments (MoM) multilevel fast multipole algorithm volume-surface integral equation

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MLFMM techniques for efficient analysis of random array configuration for SKA radio telescope

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JOURNAL OF ENGINEERING-JOE 2017年第12期2017卷 656-658页

作者： Padhi, Shantanu K. Chalmers Univ Technol Biomed Electromagnet Grp Dept Elect Engn E2 SE-41296 Gothenburg Sweden Thayer Sch Engn Dartmouth Microwave Imaging & Spect Grp Hanover NH 03755 USA

The implication of multilevel fast multipole algorithm (MLFMM) is applied to the analysis of large antenna array of the dual-polarised log-periodic dipole antenna in the presence of dielectric half-space and arranged in a random array configuration for square kilometre array (SKA) radio telescope. The MLFMM is applied to accelerate the matrix-vector product operations. The findings are compared with the results obtained by standard method-of-moment solver. Numerical results are given to demonstrate the accuracy and capability of this algorithm.

关键词： dipole antenna arrays astronomical techniques radiotelescopes square kilometre array radio telescope dielectric half-space dual-polarised log-periodic dipole antenna multilevel fast multipole algorithm SKA radio telescope random array configuration MLFMM techniques

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