Convergence of the fictitious-current model

摘要

When the fictitious-current model is applied for an electromagnetic-scattering problem, the accuracy and convergence of numerical results are sensitive to the distance /spl delta//sub t/ between the physical surface and the mathematical surface on which fictitious current sources are placed. In this model, /spl delta//sub t/ must be neither too small nor too large, since a small /spl delta//sub t/ degrades the accuracy of numerical solution, and a large /spl delta//sub t/ makes the moment matrix unsuited to numerical computation. Thus, when iterative methods are used, there is a trade-off between the convergence rate and the accuracy of numerical solution. Also, it is found that there exist resonant peaks depending on sampling distance /spl delta//sub s/, and the geometry of the scatterer. Therefore, when this model is used for CNR frequencies, spurious frequencies can be obtained. It is found that there is a linear relationship between /spl delta//sub t/ and /spl delta//sub s/ which maintains a constant condition number. Using this relation, a useful modelling method for electromagnetic problems is introduced.