- [Show abstract] [Hide abstract] ABSTRACT: In this paper, a hybrid algorithm of the MLFMA and the FGG-FG-FFT is proposed for fast analysis of multiscale EM scattering from electrically large PEC objects. For multiscale problems, both the MLFMA and the FGG-FG-FFT have their own disadvantages. However, the hybrid algorithm can more easily deal with multiscale problems, leading to higher efficiency than either of these two algorithms. Numerical examples are provided to demonstrate the validity and efficiency of the proposed method.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, an accurate and efficient full wave analysis for millimeter wave quasi-periodical structure for antenna applications is realized. By extracting all the surface wave poles of the spectral domain multilayered Green's functions, the discrete complex image method (DCIM) can be adopted to fast evaluate their counter parts in spatial domain, and the mixed potential integral equation (MPIE) for method of moments (MoM) can be constructed. With the Jerusalem cross as a patch element on a dielectric layer, a quasi-periodical structure can be organized as the geometries gradually varied. By illuminate this kind of structure with an incident plane wave, the distribution of electric current on the metal surface can be obtained by solving the MoM equation and the forward scattering cross section can be fast calculated by the conjugate gradient (CG) algorithm written in CUDA and realized in NVIDIA graphic process unit (GPU). A layered structure with a 17×17 Jerusalem crosses at 30GHz was calculated and very good agreements have been found between the proposed method and commercial EM simulator (CST), while an improvement on efficiency is realized.
- [Show abstract] [Hide abstract] ABSTRACT: In this talk, some efficient methods for the electromagnetic (EM) simulation of periodic structures are reviewed, including the Method of Lines (MoL) and the Finite Difference Frequency Domain (FDFD) method for the propagation characteristic simulation of substrate integrated waveguide (SIW), and the Partial Basic Solution Vector (PBSV) based Domain Decomposition Method (DDM) for the scattering and propagation simulation of various periodic structures etc.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, a new modeling procedure for the integral equation-based non-overlapping domain decomposition method (IE-NDDM) is proposed. First the integral equation is established on the entire PEC surface, then the entire surface is partitioned into some non-overlapping open-surfaces (called subdomains). The RWG basis functions are used to expand the equivalent surface electric current on the entire surface. Each full RWG basis function across some boundary curve is split into two half-RWG basis functions. The global MoM matrix equation is then combined with the sparse matrix equation determined by the boundary current continuity to form the complete model equation. Numerical results demonstrate the validity of the proposed method.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, an IE-ODDM with higher-order hierarchical Legendre basis functions is proposed for solving the scattering from an electrically large PEC object. Because higher-order basis functions are employed, the sizes of the meshes can be selected larger. Thence, even though the area of each subdomain is relatively larger, the number of unknowns involved in the subdomain is relatively smaller compared with the case where RWG basis functions are employed. Therefore, compared with the original IE-ODDM, our IE-ODDM requires both lower memory requirement and less time spent of reaching convergence. Two numerical results are provided to verify the validity and efficiency of the proposed method.
- [Show abstract] [Hide abstract] ABSTRACT: This paper presents the design of high gain compact size pyramidal horn lens antenna for 71-76GHz band. The horn antenna aperture is covered by a planar single layer all dielectric lens that is composed of two dimensional periodic unit cells of λ/2 periodicity and low loss (≤1dB). The unit cell is used to design a 21 unit cell × 21 unit cell flat lens which occupied an area of 42mm × 42mm × 4.35mm. The lens horn antenna is well matched (S11<10dB) from 70-80GHz without additional impedance matching layers, peak gain of [email protected] /* */ and aperture efficiency of 60% are achieved. The radiation characteristics of the lens are calculated using finite element method (HFSS) and finite integral technique (CST Microwave Studio).
- [Show abstract] [Hide abstract] ABSTRACT: We present an efficient strategy for reducing the memory requirement for the near-field matrix in the multilevel fast multipole algorithm (MLFMA) for solving multiscale electromagnetic (EM) scattering problems. A multiscale problem can obviously lower the storage efficiency of the MLFMA for the near-field matrix. This paper focuses on overcoming this shortcoming to a certain extent. A hybrid tree structure for the MLFMA that possesses two kinds of bottom-layer boxes with different edge sizes will be built to significantly reduce the memory requirement for the near-field matrix in the multiscale case compared with the single-tree-structure technique. Several numerical examples are provided to demonstrate the efficiency of the proposed scheme in the multiscale EM scattering.
- [Show abstract] [Hide abstract] ABSTRACT: A method for fast generating the VIE-MoM matrix with the SWG functions is proposed. This method makes the integrals representing the shared data independent of any quadratures and hence can ensure both the efficiency and accuracy. In the VIE-MoM, the time cost of filling the VIE-MoM matrix is prominent especially for an electrically large object. With the proposed method, the time cost of filling the VIE-MoM matrix can be reduced by about 85% compared with the traditional basis-basis matching method. Numerical examples are provided to demonstrate the efficiency and accuracy of the proposed method.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, a novel realization of the Integral Equation in combination with the fast Fourier transform for the CFIE is established by Fitting both the Green's function and its Gradient onto the nodes of a uniform Cartesian grid. The new method has been compared with several existing popular FFT-based methods, including the AIM, the IE-FFT, and the p-FFT. The accuracy of the proposed method is significantly higher than other FFT-based methods, and the method is not sensitive to both the grid spacing and the expansion order. The outstanding merit of the proposed method is that the fitting procedure is independent of the basis functions. Therefore, when the higher order basis functions would be adopted in the method of moments, only one fitting procedure for the Green's function and its gradient on a basis function support is needed to meet all of basis functions defined on this support. Some numerical examples are provided in this paper to demonstrate the accuracy and efficiency of the proposed method.
Article: Q-Band transceiver makes MIMO links
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, a method based on consecutive perturbation for the fast and accurate extraction of all useful surface- and leaky-wave modes for a lossy layered medium is proposed. The algorithm consists of two perturbation stages. In the first stage, according to the relationship for the frequency variation between the surface- and leaky-wave modes, the leaky-wave modes for a lossless medium can be tracked by consecutive frequency perturbation, with the surface-wave modes at a proper high frequency as starting points. All the surface-wave modes are extracted by a modified dichotomy method. In the second stage, a consecutive loss perturbation is performed, in which the medium's loss is increased step by step. In each perturbation step of both of the two stages, Newton-Raphson iterations are employed to update the modes on the corresponding Riemann sheet. With these discrete modes accurately extracted, a combination of the Discrete Complex-Image Method (DCIM) and the All-Modes Method can be realized for accurate evaluation of the Green's functions in the near-field and non-near-field regions, respectively. Several numerical examples demonstrated the high accuracy and efficiency of this method.
Conference Paper: Using a hybrid tree structure in the MLFMA in the multi-resolution case[Show abstract] [Hide abstract] ABSTRACT: The multilevel fast multipole algorithm (MLFMA) has been used in calculating electromagnetic scatterings from electrically large objects. The octree structure plays an important role in the MLFMA. However, in the multi-resolution case, a single octree structure may produce a larger near-field matrix. In this paper, in order to overcome this shortcoming to a certain extent, a hybrid tree structure scheme is proposed. In this scheme, there are two kinds of bottom-layer cubes with different edge size. With the hybrid tree structure, the memory requirement for the near matrix can be significantly reduced in the multi-resolution case compared with the MLFMA equipped with a single octree structure. Numerical examples are provided to demonstrate the efficiency of the proposed scheme.
Conference Paper: A novel FG-FFT method for the EFIE[Show abstract] [Hide abstract] ABSTRACT: In this paper, a novel realization of the FFT-based methods for the EFIE with high accuracy is established by fitting the Green's function onto the nodes of a uniform Cartesian grid. Like the IE-FFT, the focus of the proposed method is the Green function, but the accuracy of new method is significantly higher than that of the IE-FFT. Some numerical examples are provided to demonstrate the accuracy and efficiency of the proposed method.
- [Show abstract] [Hide abstract] ABSTRACT: A novel kind of Buffa-Christiansen (BC) functions is developed for improving the surface combined field integral equation with impedance boundary condition (CFIE-IBC) from three-dimensional imperfectly conducting objects. With difference from the original BC function in wide use, the novel BC function is dimensionless as the RWG function, which makes the L and K components of the resulting matrix element from the CFIE-IBC dimensionally homogeneous. As a result, the eigenvalue condition number of the matrix is very low, which leads to a fast-convergence solution whether the surface impedance is low or high. The CFIE-IBC with the novel BC function is combined with the overlapped domain decomposition method for reducing the memory requirement. In its application to the multilevel fast multipole algorithm, the far-field interactions can be simplified for reducing the computational cost.
Article: Transmitter/Receiver Manages MIMO
- [Show abstract] [Hide abstract] ABSTRACT: AbstractA new scheme of the integral equation fast Fourier transform for the combined field integral equation applied to electrically large objects is presented in this article. Lagrange interpolation is applied to the gradient of the Green's function on regular Cartesian grids, which is similar to the method of interpolating the Green's function. Compared with the gradient operator acting on the interpolated Green's function, the present method can provide higher accuracy with slightly more storage. The error analysis and some numerical examples are provided to demonstrate the accuracy and efficiency of the proposed scheme. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:891–896, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26697
- [Show abstract] [Hide abstract] ABSTRACT: An overlapped domain decomposition method (ODDM) combined with the combined field inte- gral equation (CFIE) with impedance boundary condition (IBC) is investigated for efficiently analyzing electromagnetic scattering by 3-D imperfectly conducting objects. When solving each subdomain, only parts of the matrices need to be stored into memory. Hence, the storage in the proposed method is much smaller for an electrically large object than that in the method of moments (MoM). Since the spurious edge effect of the currents is effectively depressed by using the buffer region, the proposed method yields accurate radar-cross-section (RCS) results within a very few outer iterations. Index Terms—Electromagnetic scattering, impedance boundary condition (IBC), overlapped domain decomposition method (ODDM).
- [Show abstract] [Hide abstract] ABSTRACT: A cubic polynomial inter/extrapolation method is in- vestigated to improve the inter/extrapolation accuracy of the ma- trix over a frequency band in the method of moments (MoM). In the method, the error of the MoM matrix in the Frobenius norm can be expressed as a product of the error coefficient and the poly- nomial component. The error coefficient is insensitive to the posi- tions of the frequency samples and the operating frequency, and hence it is practical to minimize the amplitude of the polynomial component rather than the error of matrix by optimizing the fre- quency samples. Actually, the amplitude of the polynomial compo- nent attains the minimum when the frequency samples are analyt- ically expressed in terms of the roots of the Chebyshev polynomial of degree 4. Numerical examples are presented to validate the pro- posed method.
- [Show abstract] [Hide abstract] ABSTRACT: In this short paper, a strict combined field integral equation formulation is proposed to solve electromagnetic scattering from perfect electric conductor surfaces with open boundary. The core idea of this method is to combine the magnetic field integral equation for an open surface with the traditional electric field integral equation. The method of moments equations obtained here will be solved by both stationary and non-stationary iterative methods simultaneously for large electromagnetic problems. At each step of the stationary scheme, a well-conditioned matrix equation is fast solved by using a non-stationary iterative method. The present method attains much faster convergence of iterations than traditional electric field integral equation. Both the spectral property related to the non-stationary iteration and the spectral radius associated with the stationary iteration are reported in this paper. Numerical results provided show the validity and efficiency of the present method.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, an efficient method is proposed to quickly and accurately locate all the surface wave modes of spectral Green’s functions of a layered medium. This method consists of two parts. In the first part, all the surface wave poles without considering the medium loss are located by a modified dichotomy on the real axis in the complex plane. In the second part, consecutive perturbations with respect to the medium loss are performed, which means that the medium loss is increased step by step from zero to the given value, and at each step, the Newton-Raphson algorithm is employed to find all the current poles, with the poles at the previous step as initial values. The residues of the surface wave poles are analytically calculated without any contour integral. The whole procedure is based on the recursively rational forms of spectral Green’s functions. As an application, all the surface wave poles and their residues obtained by the method proposed in this paper are applied in evaluation of the spatial Green’s functions by the discrete complex image method. Some numerical examples are provided to validate the correctness and efficiency of the proposed method. KeywordsGreen’s function-Sommerfeld integral-surface wave pole-perturbation-discrete complex image method
Southeast University (China)Nan-ching-hsü, Jiangxi Sheng, China