International Journal of Numerical Modelling-electronic Networks Devices and Fields 

About: International Journal of Numerical Modelling-electronic Networks Devices and Fields is an academic journal published by Wiley-Blackwell. The journal publishes majorly in the area(s): Computer science & Finite element method. It has an ISSN identifier of 0894-3370. Over the lifetime, 1918 publications have been published receiving 14592 citations. The journal is also known as: Numerical modelling.

Time Domain Electromagnetic Field Computation with Finite Difference Methods

Abstract: The solution of Maxwell's equations in the time domain has now been in use for almost three decades and has had great success in many different applications. The main attraction of the time domain approach, originating in a paper by Yee (1966), is its simplicity. Compared with conventional frequency domain methods it takes only marginal effort to write a computer code for solving a simple scattering problem. However, when applying the time domain approach in a general way to arbitrarily complex problems, many seemingly simple additional problems add up. We describe a theoretical framework for solving Maxwell's equations in integral form, resulting in a set of matrix equations, each of which is the discrete analogue to one of the original Maxwell equations. This approach is called Finite Integration Theory and was first developed for frequency domain problems starting about two decades ago. The key point in this formulation is that it can be applied to static, harmonic and time dependent fields, mainly because it is nothing but a computer-compatible reformulation of Maxwell's equations in integral form. When specialised to time domain fields, the method actualy contains Yee's algorithm as a subset. Further additions include lossy materials and fields of moving charges, even including fully relativistic analysis. For amny practical problems the pure time domain algorithm is not sufficient. For instance a waveguide transition analysis requires knowledge of the incoming and outgoing mode patterns for proper excitation in the time domain. This is a typical example where both frequency and time domian analysis are essential and only the combinatin yields the successful result. Typical engineers may wonder why at all one should apply time domain analysis to basically monochromatic field problems. The answer is simple: it is much faster, needs less computer memory, is more general nad typically more accurate. Speed-up factors of over 200 have been reached for realistic problems in filter and waveguide design. The small core space requirement makes time domain methods applicable on desktop computers using milions of cells, and six unknowns per cell—a dimension that has not yet been reached by frequency domain approaches. This enormous amount of mesh cells is absolutely neceesary when complex structures or structures with spacial dimensions of many wavelengths are to be studied. Our personal recod so far is a waveguide problem in which we used 72,000,000 unknowns.

A consistent subgridding scheme for the finite difference time domain method

Abstract: Recently, the simulation of high frequency devices has become of increasing importance due to the demand for faster development processes. The Finite Difference Time Domain (FDTD) method has been proved to be an efficient tool for the simulation of electromagnetic phenomena. In the paper we derive a new consistent three-dimensional subgridding scheme for the Finite Integration Technique. In the time domain the latter method reduces to FDTD when only cubical cells are used. The subgridding extension can help to achieve accurate models of small structure details without heavily decreasing numerical efficiency while the properties of continuous Maxwell equations are still conserved in the grid space. After studying numerical dispersion and stability, the applicability of the method is demonstrated by regarding an example studying scattering at a small post in a rectangular waveguide.

Yee‐like schemes on a tetrahedral mesh, with diagonal lumping

Abstract: SUMMARY A Galerkin edge-element solution technique for Maxwell’s equations in time domain is discussed. With proper diagonal lumping of one of the mass matrices, it can be seen as a generalization to a tetrahedral mesh and its barycentric dual of the staggered-grid "nite di!erence scheme known nowadays as FDTD, or Yee’s scheme. A new approach to the lumping, backed by a speci"c convergence-proof technique, is proposed. Copyright ( 1999 John Wiley & Sons, Ltd.

Complex space approach to perfectly matched layers: a review and some new developments

Abstract: We discuss the interpretation of the perfectly matched layer (PML) absorbing boundary condition (ABC) as an analytic continuation of the coordinate space to a complex variables spatial domain (complex space). The generalization of the PML to curvilinear coordinates and to general linear media using this rationale is reviewed and summarized. The analytic continuation is shown to be equivalent to a change on the metric of the space. By using such geometric viewpoint on the PML, we then discuss the various PML formulations in connection with fundamental symmetries of Maxwell's equations. Copyright © 2000 John Wiley & Sons, Ltd.

Approximate formulae for numerical inversion of Laplace transforms

Abstract: Most methods for the numerical calculation of inverse Laplace transformations f(t) = L−1[F(s)] have serious limitations concerning the class of functions F(s) that can be inverted or the achievable accuracy. The procedures described in the paper can be used to invert rational as well as irrational or transcendental functions of the complex variable s. The required accuracy of the results can be enhanced without changing the algorithm, only at the cost of a longer computation time. The described methods were verified with many examples including transients in lumped/distributed systems with sections of lossy multiconductor transmission lines or with distributed RC elements. © 1998 John Wiley & Sons, Ltd.