Asymptotic Waveform Evaluation Technique Research Articles

An Evaluated PMCHWT Solution of EM Scattering for Mutimedium Targets With Variant Permittivities

An evaluated PMCHWT is formulated in terms of the asymptotic waveform evaluation (AWE) technique to predict the scattering characteristics of multi-medium targets. At first the uncertain dielectric constant can vary within a certain range by setting it as the permittivity variable. Then the evaluated PMCHWT is constructed with these permittivity variables. Noted that the inversion of the impedance matrix is needed only once and the moment matching technique is used in the process of recursion. Moreover, the high-order derivatives are applied in order to obtain the greater convergence radius. Finally, the impedance matrix, right vector and the current density are expanded with the Taylor series. And the current density is approximated by the reduced order rational Padé function. Compared with the traditional perturbation method, greater radius of convergence can be obtained by using the proposed method. In addition, higher efficiency can be gotten than the general Monte Carlo (MC) method.

A-EFIE With Model-Order Reduction Technique for Fast Analysis of Circuit Simulation

A fast frequency-sweep method for microwave circuit simulation based on a full-wave solver is presented in this letter. The complexity of the mathematical model of the augmented electric field integral equation (A-EFIE) system is reduced by employing the model-order reduction (MOR) technique, where the reduced-order subspace is constructed by singular value decomposition (SVD). Compared to the A-EFIE with the asymptotic waveform evaluation (AWE) technique, the A-EIFE with the SVD-based MOR technique can speed up the broadband circuit analysis more efficiently.

Research on wide-band electromagnetic scattering characteristics of random distributed objects using Monte Carlo method

In the engineering applications, the distribution of objects is mostly random. Therefore, scattering analysis of randomly distributed objects has been one of the important problems in broadband electromagnetic calculation field. To resolve the problem, the Asymptotic Waveform Evaluation technique in conjunction with Monte Carlo Method is presented. First, the stochastic distribution is modeled by the Monte Carlo Method, and then the Asymptotic Waveform Evaluation technique using Padé approximation is utilized to achieve the Radar Cross Section at a wide frequency band. Numerical results show that the Asymptotic Waveform Evaluation technique can solve the random distributed object problems efficiently and accurately.

Fast simulations of electromagnetic scattering from rough surface over a frequency band using asymptotic waveform evaluation technique: horizontal polarization

The asymptotic waveform evaluation (AWE) technique combined with the scalar integral equation and the tapered plane wave is chosen to fast simulate the electromagnetic scattering from rough surface over a frequency band under horizontal (H) polarization in this paper. The tapered plane wave with the energy in a narrow beam is chosen as the incident wave to avoid the artificial edge diffraction due to the finite length of the simulated rough surface. And the scalar integral equation is used to obtain the surface unknowns along the rough surface induced by the incident wave. The validity and efficiency of the AWE are shown by comparing with the repeated calculation at every finer frequency increment through the method of moments (MoM). The influences of several important parameters, such as root-mean-square height, correlation length and incident angle are studied and discussed. And in this paper, the complex frequency hopping technique is also used to extend the validity of AWE.

Analysis of Fourier and Non-Fourier heat conduction using Tiknonov based Well-conditioned Asymptotic Waveform Evaluation Technique

Analysis of Fourier and Non-Fourier heat conduction using Tiknonov based Well-conditioned Asymptotic Waveform Evaluation Technique

Fast Frequency Sweep Using Asymptotic Waveform Evaluation Technique and Thin Dielectric Sheet Approximation

The thin dielectric sheet (TDS) surface integral equation (SIE) combined with the asymptotic waveform evaluation (AWE) technique is proposed to efficiently analyze wideband properties of thin dielectric layers such as radome and composite materials. The TDS SIE is an efficient method for analyzing the thin dielectric layer because the number of unknowns of the TDS SIE is fewer than that of the volume integral equation (VIE) and the condition number of the TDS impedance matrix is small. In addition, the AWE technique based on a Taylor series and the Pade approximation is a well-known method for fast frequency sweep. Therefore, the combination of these two methods makes analysis of the thin dielectric layer efficient in the wide frequency region because the advantages of each method are shown at the same time. In order to determine the valid bandwidth of the approximated results for arbitrary problems using the TDS combined with the AWE, the bandwidth estimation approach for the AWE is applied. The results of the proposed method for closed and open structures agree very well with the exact solutions and reveal the capability for fast frequency sweep.

Fast scattering analysis over a wide frequency band using Clenshaw–Lord‐type Pade–Chebyshev approximation

Pade–Chebyshev approximation of Clenshaw–Lord type with method of moments is proposed for wide-band analysis of an arbitrary-shaped perfect electric conductor structure. Moreover, various Chebyshev polynomials, such as first, third, and fourth kinds, are used to express the singular points in the graph to display the expected result for scattering characteristics. The proposed algorithm has a wide radius of convergence due to the use of Chebyshev polynomials and improves calculation speed because Clenshaw–Lord-type Pade approximation requires fewer sampling points than Maehly-type Pade approximation in the derivation of the rational function. The results of the proposed method agree very well with the exact solution and reveal its possibility of obtaining more accurate solution than the asymptotic waveform evaluation technique.

Frequency sweep computation of half‐space scattering using asymptotic waveform evaluation

ABSTRACTThe asymptotic waveform evaluation (AWE) technique is applied to mixed potential integral equation (MPIE) for fast frequency sweep in half‐space scattering analysis. The AWE procedure requires the evaluation of high order derivative of impedance matrices that consist of complicated Green's function of layered media. Pseudo‐spectral method, a numerical differentiation approach, is employed to calculate these derivatives. Numerical experiments show that AWE technique improves the efficiency of scattering computation in half‐space structure. Furthermore, the presented approach can handle dispersive media. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:495–498, 2016

Tickhonov based well-condition asymptotic waveform evaluation for dual-phase-lag heat conduction

The Tickhonov based well condition asymptotic waveform evaluation (TWCAWE) is presented here to study the non-Fourier heat conduction problems with various boundary conditions. In this paper, a novel TWCAWE method is proposed to overwhelm ill-conditioning of the asymptotic waveform evaluation (AWE) technique for thermal analysis and also presented for time-reliant problems. The TWCAWE method is capable to evade the instability of AWE and also efficaciously approximates the initial high frequency and delay similar as well-established numerical method, such as Runge-Kutta (R-K). Furthermore, TWCAWE method is found 1.2 times faster than the AWE and also 4 times faster than the traditional R-K method.

A hybrid broadband analysis approach for surface-wire junctions structures by applying AIM and asymptotic waveform evaluation technique

The asymptotic waveform evaluation (AWE) technique is utilized to deal with broadband electromagnetic problems of surface–wire junction geometries in this paper. To ensure the current continuity, triangles-to-segments junction model is used and the Rao–Wilton–Glisson (RWG) and triangular basis functions are used to solve the distributions of current on perfect electric conductor and wire, respectively. Then, the current on surface conductor, wire, and junctions are expanded in a rational function via Padé approximation. The AWE technique needs to store the high-order derivatives of the self-impedance and mutual-impedance matrices of surface–wire, which increase the memory requirements. Thus, the adaptive integral method is employed to reduce memory requirements and to accelerate the matrix-vector multiplications in an iterative solver. Finally, some numerical examples are shown to demonstrate the efficiency and accuracy of the proposed method

Efficient Analysis of Surface‐Wire Configurations Using AIM and Best Uniform Rational Approximation

The Adaptive integral method (AIM) in conjunction with the best uniform approximation technique is applied to analyze the electromagnetic problems of surface-wire junction geometries over a wide frequency band. To improve the computation efficiency, the best uniform approximation method is utilized. The AIM can reduce memory requirements and accelerate the matrix-vector multiplications in iterative process. Some numerical examples are shown to demonstrate the efficiency and accuracy of the proposed method. Compared with the direct solution method and Asymptotic waveform evaluation (AWE) technique, the proposed technique is found to be efficient in a broadband with the lower Central processing unit (CPU) time required and without loss of accuracy.

Fast and accurate analysis of broadband RCS using method of moments with loop‐tree basis functions

An efficient method for wide-band electromagnetic (EM) scattering properties analysis of three-dimensional arbitrarily shaped perfectly electric conductor (PEC) objects is proposed in this study. The electric field integral equation (EFIE) is solved by the method of moments (MoM) base on the loop-tree basis functions. The EM properties not only can be achieved accurately in high frequency band, but also in low frequency band within the desired bandwidth using loop-tree basis functions. To improve the computation efficiency, the Maehly approximation method is utilised. Compared with the direct solution method and asymptotic waveform evaluation technique, the proposed technique is found to be efficient in a broadband and wide angular domain with the lower central processing unit time required and without loss of accuracy.

Scattering analysis of curved FSS using Floquet harmonics and asymptotic waveform evaluation technique

In this paper, we present the scattering characteristics of infinite and finite array using method of moment (MoM) with Floquet harmonics and asymptotic waveform evaluation (AWE) technique. First, infinite cylindrical dipole array is analyzed using the MoM with entire domain basis function and cylindrical Floquet harmonics. To provide the validity of results, we fabricated the cylindrical dipole array and measured the transmission characteristics. The results show good agreements. Second, we analyzed the scattering characteristics of finite array. A large simulation time is needed to obtain the scattering characteristics of finite array over wide frequency range because Floquet harmonics can`t be applied. So, we used the MoM with AWE technique using Taylor series and Pade approximation to overcome the shortcomings of conventional MoM. We calculated the radar cross section (RCS) as scattering characteristics using the proposed method in this paper and the conventional MoM for finite planar slot array, finite spherical slot array, and finite cylindrical dipole array, respectively. The compared results agree well and show that the proposed method in this paper is good for electromagnetic analysis of finite FSS.

Solutions of Broadband RCS Using AWE Technique and Equivalent Dipole Moment Method

A broadband radar cross section (RCS) calculation approach is proposed based on the asymptotic waveform evaluation (AWE) technique. The equivalent dipole moment method (EDMM) is used to accelerate the process of filling the impedance matrix and more derivative matrices. So the broadband RCS is achieved quickly by using AWE technique and EDMM. Numerical results show that the computational efficiency is improved significantly by using the method presented in this paper with ensuring the accuracy.

Fast analysis of electromagnetic scattering characteristics in spatial and frequency domains based on compressive sensing

Method of moments (MOM) is a common numerical method for solving electromagnetics, which is used widely owing to its high accuracy. As the traditional MOM is applied to solving electromagnetic problem in both spatial and frequency domains, the matrix equation generated from the integral equation must be solved repeatedly since small spatial increments and frequency increments are both required. To resolve problems of this kind, the compressive sensing (CS) theory combined with the asymptotic waveform evaluation (AWE) is introduced to form a new efficient computational method. Firstly, a new incident source is constructed based on CS theory, in which much spatial information is included. Secondly, illuminated by the new incident source, the new equation is solved by AWE technique, and finally a fast implement is formed for solving electromagnetic scattering characteristics in both spatial and frequency domains.

Application of Asymptotic Waveform Evaluation to Hybrid FE-BI-MLFMA for Fast RCS Computation Over a Frequency Band

The asymptotic waveform evaluation (AWE) technique has been widely used in the method of moment (MoM), the finite element method (FEM), and the hybrid finite element-boundary integral method (FE-BI) for fast computation over a wide frequency band. However, how to apply AWE to the multilevel fast multipole algorithm (MLFMA) still remains challenge. This paper proposes an efficient and robust approach to apply AWE to the hybrid finite element-boundary integral-multilevel fast multipole algorithm (FE-BI-MLFMA). The validity of the proposed approach is verified by numerical examples for scattering problems. Numerical experiments show that the application of AWE to FE-BI-MLFMA can greatly improve the efficiency of FE-BI-MLFMA for computation of scattering over a wide frequency band.

Efficient Wide-Band Analysis of Antennas Around a Conducting Platform Using MoM-PO Hybrid Method and Asymptotic Waveform Evaluation Technique

An efficient wide-band analysis that combines method of moments-physical optics (MoM-PO) hybrid formulation with the asymptotic waveform evaluation (AWE) technique is presented for antennas around an electrically large platform. To facilitate the analysis of large problems, compared with MoM, the MoM-PO hybrid formulation is employed to reduce the number of unknowns and memory requirements. Further, the automatic differentiation (AD) approach is used to calculate the high order frequency derivatives of Green's functions required in the algorithm. Numerical results show the efficiency and capability of the method proposed in this paper.

Wavelet Based MBPE Technique for Fast RCS Computation of DNG Metamaterials

Described by the drude model, the DNG metamaterials is essentially a dispersive media, the scattering analysis of it over broad band by asymptotic waveform evaluation (AWE) technique is difficult since the computation of high order differential coefficients for the impedance matrix elements, to reduce the differential order, the model-based parameter estimation (MBPE) technique based on two expanded points is applied to analysis the scattering characters of double-negative (DNG) metamaterials. A wavelet matrix transform (WMT) is used to get a sparse matrix equation in wavelet-domain, which is solved over a broad frequency band by the MBPE. As compared with AWE, the MBPE technique obtained more accurate results over a broader frequency band.

Fast and Accurate Wide-Band Analysis of Antennas Mounted on Conducting Platform Using AIM and Asymptotic Waveform Evaluation Technique

The adaptive integral method (AIM) in conjunction with the asymptotic waveform evaluation (AWE) technique is presented for wide-band analysis of antennas in the presence of electrically large conducting platforms. In the AWE technique, the Pade approximation solution obtained by matching the coefficients of the Taylor series (namely, moments) is utilized to achieve fast frequency sweeping. Besides the calculation and storage of the high order frequency derivatives of impedance matrices, the AWE technique requires repeatedly solving the linear system for the moments. Thus the AIM is employed to reduce matrix storage and to accelerate all the matrix-vector multiplications in both the linear system for the moments and the iterative solver. Furthermore, a localized self-box inclusion (SBI) preconditioner is used to accelerate the solution procedure of the linear system for the moments. Finally, three numerical examples are given and discussed. The input admittance and return loss of the antennas over a given frequency band are obtained by AIM and AIM-AWE method, respectively. The good agreements show that the proposed hybrid technique can greatly reduce the computation time without loss of accuracy.

UTD solution for the diffraction by an anisotropic impedance wedge at arbitrary skew incidence: numerical matching method

a numerical matching method (NMM) based on the framework of the uniform geometrical theory of diffraction (UTD) is proposed to build the spectral functions for computing the diffraction field by anisotropic impedance wedge at an arbitrary skew incidence. The NMM starts from the coupled integral equations before they are converted into the coupled difference equations as the classic Maliuzhinets methods. Then, the spectral function in the Sommerfeld integral representation of the longitudinal components of the EM field is expanded by a series about the spectrum and the skew incident angle with unknown coefficients. With respect to the oblique incident angle based on normal to the edge incidence or grazing to the edge incidence, the spectral function is derived numerically by solving a system of algebraic equations constructed from the coupled integral equations, after choosing the numerical matching regions on the wedge faces and setting a Sommerfeld numerical integration path. On the basis of the sampled incidences, the asymptotic waveform evaluation (AWE) technique is employed to deduce the spectral function at any other skew incidence in the whole angle space (0°-90°) rapidly. Finally, the UTD solutions are provided far beyond the applicability of the perturbation approach and the numerical examples provide a uniform behavior of the field with respect to the observation angle.