Pub Date : 2022-06-23DOI: 10.1109/JMMCT.2022.3185531
Cedric Münger;Kristof Cools
We present a method for the numerical evaluation of 6D and 5D singular integrals appearing in Volume Integral Equations. It is an extension of the Sauter-Schwab/Taylor-Duffy strategy for singular triangle-triangle interaction integrals to singular tetrahedron-tetrahedron and triangle-tetrahedron interaction integrals. The general advantages of these kind of quadrature strategy is that they allow the use of different kinds of kernel and basis functions. They also work on curvilinear domains. They are all based on relative coordinates tranformation and splitting the integration domain into subdomains for which quadrature rules can be constructed. We show how to build these tensor-product quadrature rules in 6D and 5D and further show how to improve their efficiency by using quadrature rules defined over 2D, 3D and 4D simplices. Compared to the existing approach, which computes the integral over the subdomains as a sequence of 1D integrations, significant speedup can be achieved. The accuracy and convergence properties of the method are demonstrated by numerical experiments for 5D and 6D singular integrals. Additionally, we applied the new quadrature approach to the triangle-triangle interaction integrals appearing in Surface Integral Equations.
{"title":"Efficient Numerical Evaluation of Singular Integrals in Volume Integral Equations","authors":"Cedric Münger;Kristof Cools","doi":"10.1109/JMMCT.2022.3185531","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3185531","url":null,"abstract":"We present a method for the numerical evaluation of 6D and 5D singular integrals appearing in Volume Integral Equations. It is an extension of the Sauter-Schwab/Taylor-Duffy strategy for singular triangle-triangle interaction integrals to singular tetrahedron-tetrahedron and triangle-tetrahedron interaction integrals. The general advantages of these kind of quadrature strategy is that they allow the use of different kinds of kernel and basis functions. They also work on curvilinear domains. They are all based on relative coordinates tranformation and splitting the integration domain into subdomains for which quadrature rules can be constructed. We show how to build these tensor-product quadrature rules in 6D and 5D and further show how to improve their efficiency by using quadrature rules defined over 2D, 3D and 4D simplices. Compared to the existing approach, which computes the integral over the subdomains as a sequence of 1D integrations, significant speedup can be achieved. The accuracy and convergence properties of the method are demonstrated by numerical experiments for 5D and 6D singular integrals. Additionally, we applied the new quadrature approach to the triangle-triangle interaction integrals appearing in Surface Integral Equations.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950338","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}
The implicit locally one-dimensional finite-difference time-domain (LOD-FDTD) method is useful for designing plasmonic devices and waveguide structures. By using a large timestep size, the implicit LOD-FDTD method can reduce the computational time; however, this involves a trade-off with accuracy. To overcome this trade-off, we propose an error-controllable scheme for the LOD-FDTD method, wherein the fast inverse Laplace transform is employed to generate the electromagnetic field in arbitrary time domain from that in complex frequency domain. Compared to the conventional LOD-FDTD method, our scheme provides higher accuracy with more efficient calculations.
{"title":"Error-Controllable Scheme for the LOD-FDTD Method","authors":"Tasuku Nakazawa;Di Wu;Seiya Kishimoto;Jun Shibayama;Junji Yamauchi;Shinichiro Ohnuki","doi":"10.1109/JMMCT.2022.3181568","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3181568","url":null,"abstract":"The implicit locally one-dimensional finite-difference time-domain (LOD-FDTD) method is useful for designing plasmonic devices and waveguide structures. By using a large timestep size, the implicit LOD-FDTD method can reduce the computational time; however, this involves a trade-off with accuracy. To overcome this trade-off, we propose an error-controllable scheme for the LOD-FDTD method, wherein the fast inverse Laplace transform is employed to generate the electromagnetic field in arbitrary time domain from that in complex frequency domain. Compared to the conventional LOD-FDTD method, our scheme provides higher accuracy with more efficient calculations.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/7274859/9715154/09793664.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.1109/JMMCT.2022.3181606
Xu Zhang;Jiaxin Wan;Zhuoyang Liu;Feng Xu
Radar cross section (RCS) optimization is important to object geometry design, for example seeking a low-scattering structure. However, it is difficult to obtain a geometry with particular RCS quickly due to the complex geometry, low-efficient RCS calculation, or lack of effective automatic optimization methods. In this paper, a RCS optimization method is proposed based on physics inspired neural network named electromagnetic fully connected neural network (EM-FCNN). It employs the principles of MoM to transform the slow numerical calculation method into the fast neural network calculation. To reduce the complexity of surface geometry characterization, a low-dimensional surface hyperparametric modulation method (SHMM) is formulated to characterize object surfaces by introducing a modulation factor into rough surfaces. In this regard, the ultra-high-dimensional target surfaces can be characterized by only a few hyperparameters. To accelerate the optimization process, a dimensional reduction optimization algorithm (DROA) is further designed to simplify the multi-dimensional hyperparameters optimization problem to a series of one-dimensional optimization problems. The efficacy of the proposed method is validated with a RCS reduction task of a simplified aircraft model. This is generalized to solve the RCS optimization and it can be used to handle object geometry design for other application areas.
{"title":"RCS Optimization of Surface Geometry With Physics Inspired Neural Networks","authors":"Xu Zhang;Jiaxin Wan;Zhuoyang Liu;Feng Xu","doi":"10.1109/JMMCT.2022.3181606","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3181606","url":null,"abstract":"Radar cross section (RCS) optimization is important to object geometry design, for example seeking a low-scattering structure. However, it is difficult to obtain a geometry with particular RCS quickly due to the complex geometry, low-efficient RCS calculation, or lack of effective automatic optimization methods. In this paper, a RCS optimization method is proposed based on physics inspired neural network named electromagnetic fully connected neural network (EM-FCNN). It employs the principles of MoM to transform the slow numerical calculation method into the fast neural network calculation. To reduce the complexity of surface geometry characterization, a low-dimensional surface hyperparametric modulation method (SHMM) is formulated to characterize object surfaces by introducing a modulation factor into rough surfaces. In this regard, the ultra-high-dimensional target surfaces can be characterized by only a few hyperparameters. To accelerate the optimization process, a dimensional reduction optimization algorithm (DROA) is further designed to simplify the multi-dimensional hyperparameters optimization problem to a series of one-dimensional optimization problems. The efficacy of the proposed method is validated with a RCS reduction task of a simplified aircraft model. This is generalized to solve the RCS optimization and it can be used to handle object geometry design for other application areas.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950262","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 : 2022-06-08DOI: 10.1109/JMMCT.2022.3180550
Youngno Youn;Jaehong Choi;Daehyeon Kim;Ahmed Abdelmottaleb Omar;Jaehyun Choi;Suho Chang;Inseop Yoon;Seung-Tae Ko;Jungyub Lee;Youngju Lee;Mobayode O. Akinsolu;Bo Liu;Wonbin Hong
This paper presents a new accurate and efficient design methodology for complex integrated lens antenna (ILA), to achieve wide-angle beam coverage with scan loss mitigation at the millimeter-wave (mmWave) spectrum. The proposed ILA comprises inhomogeneous curvatures with internal and external center off-sets, in which multiple parameters instigate high order and non-linear behaviors. A two-dimensional (2-D) ray-tracing model is used to estimate the refractions on the elliptically curved boundaries based on geometrical optics. This approach is integrated into the particle swarm optimization of the 2-D ray-tracing model to determine the near-optimum geometric configuration of the ILA. Denoted as Geometric Optics-based Multiple Scattering (GOMS), the computational memory usage is reduced by a factor of 10,000 using this approach. The devised ILA achieves a wide-angle beam coverage of 156° with a scan loss of 2.10 dB alongside a broad impedance bandwidth of 35.0 GHz to 42.0 GHz. The measurement results for the performance of the fabricated prototype of the ILA validate the wide-angle scanning with scan loss mitigation inferred from the simulation results. This confirms the effectiveness of this method for complex design challenges involving multi-variants and restricted computational resources.
{"title":"Dome-Shaped mmWave Lens Antenna Optimization for Wide-Angle Scanning and Scan Loss Mitigation Using Geometric Optics and Multiple Scattering","authors":"Youngno Youn;Jaehong Choi;Daehyeon Kim;Ahmed Abdelmottaleb Omar;Jaehyun Choi;Suho Chang;Inseop Yoon;Seung-Tae Ko;Jungyub Lee;Youngju Lee;Mobayode O. Akinsolu;Bo Liu;Wonbin Hong","doi":"10.1109/JMMCT.2022.3180550","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3180550","url":null,"abstract":"This paper presents a new accurate and efficient design methodology for complex integrated lens antenna (ILA), to achieve wide-angle beam coverage with scan loss mitigation at the millimeter-wave (mmWave) spectrum. The proposed ILA comprises inhomogeneous curvatures with internal and external center off-sets, in which multiple parameters instigate high order and non-linear behaviors. A two-dimensional (2-D) ray-tracing model is used to estimate the refractions on the elliptically curved boundaries based on geometrical optics. This approach is integrated into the particle swarm optimization of the 2-D ray-tracing model to determine the near-optimum geometric configuration of the ILA. Denoted as Geometric Optics-based Multiple Scattering (GOMS), the computational memory usage is reduced by a factor of 10,000 using this approach. The devised ILA achieves a wide-angle beam coverage of 156° with a scan loss of 2.10 dB alongside a broad impedance bandwidth of 35.0 GHz to 42.0 GHz. The measurement results for the performance of the fabricated prototype of the ILA validate the wide-angle scanning with scan loss mitigation inferred from the simulation results. This confirms the effectiveness of this method for complex design challenges involving multi-variants and restricted computational resources.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950335","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 : 2022-04-26DOI: 10.1109/JMMCT.2022.3169460
Thomas E. Roth;Weng C. Chew
The spontaneous emission rate (SER) is an important figure of merit for any quantum bit (qubit), as it can play a significant role in the control and decoherence of the qubit. As a result, accurately characterizing the SER for practical devices is an important step in the design of quantum information processing devices. Here, we specifically focus on the experimentally popular platform of a transmon qubit, which is a kind of superconducting circuit qubit. Despite the importance of understanding the SER of these qubits, it is often determined using approximate circuit models or is inferred from measurements on a fabricated device. To improve the accuracy of predictions in the design process, it is better to use full-wave numerical methods that can make a minimal number of approximations in the description of practical systems. In this work, we show how this can be done with a recently developed field-based description of transmon qubits coupled to an electromagnetic environment. We validate our model by computing the SER for devices similar to those found in the literature that have been well-characterized experimentally. We further cross-validate our results by comparing them to simplified lumped element circuit and transmission line models as appropriate.
{"title":"Full-Wave Methodology to Compute the Spontaneous Emission Rate of a Transmon Qubit","authors":"Thomas E. Roth;Weng C. Chew","doi":"10.1109/JMMCT.2022.3169460","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3169460","url":null,"abstract":"The spontaneous emission rate (SER) is an important figure of merit for any quantum bit (qubit), as it can play a significant role in the control and decoherence of the qubit. As a result, accurately characterizing the SER for practical devices is an important step in the design of quantum information processing devices. Here, we specifically focus on the experimentally popular platform of a transmon qubit, which is a kind of superconducting circuit qubit. Despite the importance of understanding the SER of these qubits, it is often determined using approximate circuit models or is inferred from measurements on a fabricated device. To improve the accuracy of predictions in the design process, it is better to use full-wave numerical methods that can make a minimal number of approximations in the description of practical systems. In this work, we show how this can be done with a recently developed field-based description of transmon qubits coupled to an electromagnetic environment. We validate our model by computing the SER for devices similar to those found in the literature that have been well-characterized experimentally. We further cross-validate our results by comparing them to simplified lumped element circuit and transmission line models as appropriate.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950112","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 : 2022-04-05DOI: 10.1109/JMMCT.2022.3164679
Shuo Liu;Eng Leong Tan;Bin Zou
The commonly used unconditionally stable finite-difference time-domain (FDTD) methods such as alternating direction implicit (ADI)-FDTD, and its one-step formulation, leapfrog ADI-FDTD, have been found to violate the divergence condition of Gauss's law. The recently proposed leapfrog complying-divergence implicit (CDI)-FDTD not only addresses this problem, but also features many advantages, including unconditional stability, minimal floating-point operations and one-step leapfrog update. To further expand its application, this paper presents the incident plane-wave source formulations for leapfrog CDI-FDTD. Two stable and efficient formulations with different advantages are presented for introducing the far-zone plane-wave source into the FDTD problem space, namely, the scattered-field (SF) formulation and total-field / scattered field (TF/SF) formulation. To deal with the discontinuity and inconsistency across TF/SF boundaries, the fields on the boundaries need special treatments with careful modifications to ensure stability and proper plane-wave injection. Numerical results show that the incident fields can be effectively injected into the problem space with the stability of leapfrog CDI-FDTD maintained in both formulations. In addition, comparisons of radar cross sections computed using leapfrog CDI-FDTD, leapfrog ADI-FDTD and explicit FDTD with both SF and TF/SF formulations are presented. These demonstrate the advantages of leapfrog CDI-FDTD method in solving far-zone plane-wave source problems, including high efficiency, unconditional stability and complying divergence.
{"title":"Incident Plane-Wave Source Formulations for Leapfrog Complying-Divergence Implicit FDTD Method","authors":"Shuo Liu;Eng Leong Tan;Bin Zou","doi":"10.1109/JMMCT.2022.3164679","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3164679","url":null,"abstract":"The commonly used unconditionally stable finite-difference time-domain (FDTD) methods such as alternating direction implicit (ADI)-FDTD, and its one-step formulation, leapfrog ADI-FDTD, have been found to violate the divergence condition of Gauss's law. The recently proposed leapfrog complying-divergence implicit (CDI)-FDTD not only addresses this problem, but also features many advantages, including unconditional stability, minimal floating-point operations and one-step leapfrog update. To further expand its application, this paper presents the incident plane-wave source formulations for leapfrog CDI-FDTD. Two stable and efficient formulations with different advantages are presented for introducing the far-zone plane-wave source into the FDTD problem space, namely, the scattered-field (SF) formulation and total-field / scattered field (TF/SF) formulation. To deal with the discontinuity and inconsistency across TF/SF boundaries, the fields on the boundaries need special treatments with careful modifications to ensure stability and proper plane-wave injection. Numerical results show that the incident fields can be effectively injected into the problem space with the stability of leapfrog CDI-FDTD maintained in both formulations. In addition, comparisons of radar cross sections computed using leapfrog CDI-FDTD, leapfrog ADI-FDTD and explicit FDTD with both SF and TF/SF formulations are presented. These demonstrate the advantages of leapfrog CDI-FDTD method in solving far-zone plane-wave source problems, including high efficiency, unconditional stability and complying divergence.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950100","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 : 2022-04-05DOI: 10.1109/JMMCT.2022.3164942
Osman Goni;Vladimir I. Okhmatovski
A novel magnetic current based Surface-Volume-Surface Electric Field Integral Equation (SVS-EFIE-M) is presented for the problem of scattering on homogeneous non-magnetic dielectric objects. The exact Galerkin Method of Moments (MoM) utilizing both the rotational and irrotational vector spherical harmonics as orthogonal basis and test functions according to the Helmholtz decomposition is implemented to solve SVS-EFIE-M analytically for the case of dielectric sphere excited by an electric dipole. The field throughout the sphere is evaluated and compared against the exact classical Mie series solution. The two are shown to agree to 12 digits of accuracy upon a sufficient number of basis/test functions taken in the MoM solution and the Mie series expansion. This exact solution validates the rigorous nature of the new SVS-EFIE-M formulation. It also reveals the spectral properties of its individual operators, their products and their linear combination. The spectrum of the MoM impedance matrix is also obtained. It is shown that upon choosing basis and test functions in $L^{2}(S)$ space and evaluating testing inner products in the same space, the MoM impedance matrix features bounded condition number with increasing order of discretization and/or at low frequencies. This makes the proposed SVS-EFIE-M formulation free of oversampling and low-frequency breakdowns giving it advantage both over its SVS-EFIE-J predecessor and classical double-source integral equations such as PMCHWT, Muller, and others suffering from this type of numerical instabilities inherent to their inferior spectral properties.
{"title":"Exact Solution of New Magnetic Current Based Surface-Volume-Surface EFIE and Analysis of Its Spectral Properties","authors":"Osman Goni;Vladimir I. Okhmatovski","doi":"10.1109/JMMCT.2022.3164942","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3164942","url":null,"abstract":"A novel magnetic current based Surface-Volume-Surface Electric Field Integral Equation (SVS-EFIE-M) is presented for the problem of scattering on homogeneous non-magnetic dielectric objects. The exact Galerkin Method of Moments (MoM) utilizing both the rotational and irrotational vector spherical harmonics as orthogonal basis and test functions according to the Helmholtz decomposition is implemented to solve SVS-EFIE-M analytically for the case of dielectric sphere excited by an electric dipole. The field throughout the sphere is evaluated and compared against the exact classical Mie series solution. The two are shown to agree to 12 digits of accuracy upon a sufficient number of basis/test functions taken in the MoM solution and the Mie series expansion. This exact solution validates the rigorous nature of the new SVS-EFIE-M formulation. It also reveals the spectral properties of its individual operators, their products and their linear combination. The spectrum of the MoM impedance matrix is also obtained. It is shown that upon choosing basis and test functions in \u0000<inline-formula><tex-math>$L^{2}(S)$</tex-math></inline-formula>\u0000 space and evaluating testing inner products in the same space, the MoM impedance matrix features bounded condition number with increasing order of discretization and/or at low frequencies. This makes the proposed SVS-EFIE-M formulation free of oversampling and low-frequency breakdowns giving it advantage both over its SVS-EFIE-J predecessor and classical double-source integral equations such as PMCHWT, Muller, and others suffering from this type of numerical instabilities inherent to their inferior spectral properties.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950264","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 : 2022-03-20DOI: 10.1109/JMMCT.2022.3176245
Grigorios P. Zouros;Georgios D. Kolezas;Konstantinos Katsinos
We employ the extended boundary condition method (EBCM) and construct a solution for the problem of electromagnetic (EM) scattering by anisotropic core-shell bodies of revolution (BoRs). In particular, two different core-shell configurations are examined: the gyroelectric-isotropic and the isotropic-gyroelectric setup. To construct the solution, we employ two groups of integral representations (IRs)—one group for each configuration solved—in conjunction with the discrete eigenfunction (DE) expansion of the fields in terms of spherical vector wave functions (SVWFs) for the gyroelectric regions. We demonstrate the validity and the computational performance of the method by comparisons with the HFSS commercial software for various core-shell setups such as spheroidal, cylindrical, and combined spherical-cylindrical BoRs. We also employ ADDA, a particular version of the discrete dipole approximation (DDA) method, to trace the boundaries of validity of the EBCM. Finally, we present an application of the method to the study of magnetically-tunable spheroidal THz antennas. The method can be used in a variety of potential EM applications including microwaves, functional photonics structures, as well as nanoantenna engineering.
{"title":"EM Scattering by Core-Shell Gyroelectric-Isotropic and Isotropic-Gyroelectric BoRs Using the EBCM","authors":"Grigorios P. Zouros;Georgios D. Kolezas;Konstantinos Katsinos","doi":"10.1109/JMMCT.2022.3176245","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3176245","url":null,"abstract":"We employ the extended boundary condition method (EBCM) and construct a solution for the problem of electromagnetic (EM) scattering by anisotropic core-shell bodies of revolution (BoRs). In particular, two different core-shell configurations are examined: the gyroelectric-isotropic and the isotropic-gyroelectric setup. To construct the solution, we employ two groups of integral representations (IRs)—one group for each configuration solved—in conjunction with the discrete eigenfunction (DE) expansion of the fields in terms of spherical vector wave functions (SVWFs) for the gyroelectric regions. We demonstrate the validity and the computational performance of the method by comparisons with the HFSS commercial software for various core-shell setups such as spheroidal, cylindrical, and combined spherical-cylindrical BoRs. We also employ ADDA, a particular version of the discrete dipole approximation (DDA) method, to trace the boundaries of validity of the EBCM. Finally, we present an application of the method to the study of magnetically-tunable spheroidal THz antennas. The method can be used in a variety of potential EM applications including microwaves, functional photonics structures, as well as nanoantenna engineering.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950263","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 : 2022-03-20DOI: 10.1109/JMMCT.2022.3176203
Minas Kouroublakis;Nikolaos L. Tsitsas;George Fikioris
The Method of Auxiliary Sources with an Excitation Source (MAS-ES) has been successfully employed to compute the eigenvalues of arbitrarily-shaped, simply and multiply-connected hollow waveguides with perfectly electric conducting (PEC) walls. The main advantages of this method are its simplicity, and that it is free of spurious eigenvalues, in contrast to the standard MAS approach. In this paper, we demonstrate that the MAS-ES is also effective in computing the propagation constants (eigenvalues) $beta$ of a cylindrical dielectric waveguide with core of arbitrary cross section. It is emphasized that two excitation sources (an electric and a magnetic current filament lying within the core) are required to excite hybrid modes of the dielectric waveguide; a hollow PEC waveguide requires only one source. The modified method, thus obtained, is named MAS with Two Excitation Sources (MAS-TES). The fact that the propagating modes are localized in the vicinity of the core allows us to determine the eigenvalues by measuring the response of the core to the excitation sources. This is performed by employing a response function $F(beta)$ which is maximized when a standing wave is formed in the core. Plotting $F(beta)$ for a dense set of $beta$ results in a response curve the peaks of which correspond to the waveguide’s eigenvalues. The method is tested for several dielectric waveguides’ geometries, including two multimode cases, and it is shown to be free from discrete and continuous spurious solutions. All the MAS-TES results are compared with those obtained by an FEM-based commercial software and an excellent agreement is exhibited.
本文成功地利用带激励源的辅助源方法(MAS-ES)计算了具有完全导电(PEC)壁的任意形状、简单连接和多重连接的空心波导的特征值。与标准MAS方法相比，该方法的主要优点是简单，并且没有虚假特征值。在本文中，我们证明了MAS-ES在计算具有任意截面的圆柱形介质波导的传播常数(特征值)$beta$时也是有效的。强调需要两个激发源(位于核心内的电电流和磁电流灯丝)来激发介电波导的混合模式;空心PEC波导只需要一个源。由此得到的改进方法被命名为MAS with Two Excitation Sources (MAS- tes)。传播模式在磁芯附近的局域化使得我们可以通过测量磁芯对激励源的响应来确定本征值。这是通过使用响应函数F(beta)来实现的，当驻波在核心形成时，响应函数F(beta)达到最大值。绘制$F(beta)$作为$beta$的密集集合得到响应曲线，其峰值对应于波导的特征值。该方法对几种介质波导的几何形状进行了测试，包括两种多模情况，结果表明该方法不存在离散和连续的杂散解。所有的MAS-TES结果都与基于fem的商业软件得到的结果进行了比较，显示出很好的一致性。
{"title":"Computing Eigenvalues of Dielectric Waveguides by a Method of Auxiliary Sources With Two Excitation Sources","authors":"Minas Kouroublakis;Nikolaos L. Tsitsas;George Fikioris","doi":"10.1109/JMMCT.2022.3176203","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3176203","url":null,"abstract":"The Method of Auxiliary Sources with an Excitation Source (MAS-ES) has been successfully employed to compute the eigenvalues of arbitrarily-shaped, simply and multiply-connected hollow waveguides with perfectly electric conducting (PEC) walls. The main advantages of this method are its simplicity, and that it is free of spurious eigenvalues, in contrast to the standard MAS approach. In this paper, we demonstrate that the MAS-ES is also effective in computing the propagation constants (eigenvalues) \u0000<inline-formula><tex-math>$beta$</tex-math></inline-formula>\u0000 of a cylindrical dielectric waveguide with core of arbitrary cross section. It is emphasized that two excitation sources (an electric and a magnetic current filament lying within the core) are required to excite hybrid modes of the dielectric waveguide; a hollow PEC waveguide requires only one source. The modified method, thus obtained, is named MAS with Two Excitation Sources (MAS-TES). The fact that the propagating modes are localized in the vicinity of the core allows us to determine the eigenvalues by measuring the response of the core to the excitation sources. This is performed by employing a response function \u0000<inline-formula><tex-math>$F(beta)$</tex-math></inline-formula>\u0000 which is maximized when a standing wave is formed in the core. Plotting \u0000<inline-formula><tex-math>$F(beta)$</tex-math></inline-formula>\u0000 for a dense set of \u0000<inline-formula><tex-math>$beta$</tex-math></inline-formula>\u0000 results in a response curve the peaks of which correspond to the waveguide’s eigenvalues. The method is tested for several dielectric waveguides’ geometries, including two multimode cases, and it is shown to be free from discrete and continuous spurious solutions. All the MAS-TES results are compared with those obtained by an FEM-based commercial software and an excellent agreement is exhibited.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950336","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}
In multi-dimension problems, huge sparse matrices must be calculated according to Crank-Nicolson (CN) procedure which results in degeneration of efficiency and accuracy. Based on the iterated CN procedure, domain decomposition method, an alternative scheme is proposed for the termination of unbounded uniform finite-difference time-domain domains. Meanwhile, absorbing boundary condition is proposed in the iterated CN procedure which is incorporated with the higher order concept. The proposed scheme employs the explicit scheme during the calculation rather than the implicit one. Thus, the calculation of matrices can be avoided. It shows the advantages especially in efficiency and accuracy compared with implicit schemes. Such conclusion can be further demonstrated through the numerical example. From results, it can be concluded that the proposed scheme shows efficiency improvement and accurate maintenance. Compared with other procedures, it also holds its considerable effectiveness in nonuniform domains. For comparison, it can maintain considerable performance compared with the others.
{"title":"Iterated Crank-Nicolson Procedure With Enhanced Absorption for Nonuniform Domains","authors":"Peiyu Wu;Xin Wang;Yongjun Xie;Haolin Jiang;Toshiaki Natsuki","doi":"10.1109/JMMCT.2022.3159255","DOIUrl":"https://doi.org/10.1109/JMMCT.2022.3159255","url":null,"abstract":"In multi-dimension problems, huge sparse matrices must be calculated according to Crank-Nicolson (CN) procedure which results in degeneration of efficiency and accuracy. Based on the iterated CN procedure, domain decomposition method, an alternative scheme is proposed for the termination of unbounded uniform finite-difference time-domain domains. Meanwhile, absorbing boundary condition is proposed in the iterated CN procedure which is incorporated with the higher order concept. The proposed scheme employs the explicit scheme during the calculation rather than the implicit one. Thus, the calculation of matrices can be avoided. It shows the advantages especially in efficiency and accuracy compared with implicit schemes. Such conclusion can be further demonstrated through the numerical example. From results, it can be concluded that the proposed scheme shows efficiency improvement and accurate maintenance. Compared with other procedures, it also holds its considerable effectiveness in nonuniform domains. For comparison, it can maintain considerable performance compared with the others.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2022-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49950110","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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