Computational electromagnetics

About: Computational electromagnetics is a research topic. Over the lifetime, 6412 publications have been published within this topic receiving 113727 citations. The topic is also known as: Electromagnetic field analysis.

A high-resolution interpolation at arbitrary interfaces for the FDTD method

Abstract: In recent years, the finite-difference time-domain (FDTD) method has found numerous applications in the field of computational electromagnetics. One of the strengths of the method is the fact that no elaborate grid generation specifying the content of the problem is necessary-the medium is specified by assigning parameters to the regularly spaced cubes. However, this can be a weakness, especially when the interfaces between neighboring media are curved or "sloped" and do not exactly fit the cubic lattice. Since the E- and H-fields are only calculated at the regular intervals, sharp field discontinuities at the interfaces are often missed. Furthermore, the averaging of the material properties often leads to significant errors. In this paper, a post-processing method is presented, which approximates the correct field behavior at the interfaces by interpolating between the FDTD calculated values, splitting them into the components normal and tangential to the interfaces, and then enforcing the interface conditions for each of these components separately.

High-order/spectral methods on unstructured grids I. Time-domain solution of Maxwell's equations

Abstract: We present an ab initio development of a convergent high-order accurate scheme for the solution of linear conservation laws in geometrically complex domains As our main example we present a detailed development and analysis of a scheme suitable for the time-domain solution of Maxwell''s equations in a three-dimensional domain The fully unstructured spatial discretization is made possible by the use of a high-order nodal basis, employing multivariate Lagrange polynomials defined on the triangles and tetrahedra Careful choices of the unstructured nodal grid points ensure high-order/spectral accuracy, while the equations themselves are satisfied in a discontinuous Galerkin form with the boundary conditions being enforced weakly through a penalty term Accuracy, stability, and convergence of the semi-discrete approximation to Maxwell''s equations is established rigorously and bounds on the global divergence error are provided Concerns related to efficient implementations are discussed in detail This sets the stage for the presentation of examples, verifying the theoretical results, as well as illustrating the versatility, flexibility, and robustness when solving two- and three-dimensional benchmarks in computational electromagnetics Pure scattering as well as penetration is discussed and high parallel performance of the scheme is demonstrated

Analytic Field Propagation TFSF Boundary for FDTD Problems Involving Planar Interfaces: PECs, TE, and TM

Abstract: A total-field scattered-field (TFSF) boundary can be used to introduce incident plane waves into finite-difference time-domain (FDTD) simulations. For fields which are traveling obliquely to the grid axes, there is no simple way to account fully for the effects of the inherent numerical artifacts associated with plane-wave propagation in the FDTD grid. Failure to account for these artifacts causes erroneous fields to leak across the TFSF boundary. Recent publications have proposed ways to use the dispersion relation to describe precisely plane-wave propagation in the FDTD grid thus permitting the realization of a nearly perfect TFSF boundary. However, these publications did not cover certain implementations details (such as the type of Fourier transform which is needed) or their scope was so broad as to mask the relative simplicity with which the approach can be applied to problems involving planar interfaces. This work considers the Fourier transforms needed in order for the implementation to be exact. Reflection and transmission coefficients for a planar interface are derived. Implementation for planar perfect electric conductors is also presented

Three-Dimensional Scattering and Inverse Scattering from Objects With Simultaneous Permittivity and Permeability Contrasts

Abstract: There has been increasing efforts in enhanced biomedical and geophysical imaging in the recent years exploring the magnetic contrast agent. The handling of both dielectric and magnetic contrasts adds on difficulties to the forward and inverse scattering problems. In this paper, the 3-D scattering and the inverse scattering from objects having simultaneous electric and magnetic contrasts are presented, where the permittivity, conductivity, and permeability of the objects can all be different from the background. To cope with the challenging high computation cost in the 3-D scattering problem, we formulate the combined field volume integral equations and extend the stabilized biconjugate gradient method and fast Fourier transform (BCGS-FFT) method to compute the electromagnetic field incorporating both the electric and magnetic contrasts. The variational Born iterative method for electrical contrast inversion in axisymmetric media is generalized to 3-D and to the simultaneous reconstruction of objects with electric and magnetic contrasts. The BCGS-FFT method provides the predicted scattered field from the 3-D heterogeneous objects and the Frechet derivatives in the inverse scattering problem. The efficient forward solver also dramatically reduces the computation time of the inverse problem. Numerical results are presented to validate the forward solver and to demonstrate the effectiveness of the inverse scattering method.