Measured equation of invariance solution of 2-D scattering problems using line sources as metrons

We choose /spl delta/ functions as metrons to generate MEI (measured equation of invariance) coefficients. For two-dimensional scattering problems, /spl delta/ metrons are equivalent to line sources placed on the surface of the object. The most important advantage of /spl delta/ metrons is that the corresponding measuring functions can be expressed analytically and no numerical integration is needed when computing the MEI coefficients. Considering that finding the MEI coefficients is the dominant part of the computation time consumed by the MEI method, we expect to greatly reduce the computation burden by using /spl delta/ functions instead of sinusoidal functions as metrons. Besides, /spl delta/ functions alleviate the ill-conditioning problem of the MEIC matrix. We have also found that the positioning of line sources must be investigated carefully in order to obtain convergent and accurate results. Our numerical practice shows that for geometry other than circular cylinders, uniformly distributed line sources do not always lead to convergent solutions as the number of coupled nodes increases. In this paper, we propose non-uniform positioning of /spl delta/ metrons around the object surface to guarantee stable and accurate solutions. Numerical results show the efficiency of the technique, especially in handling 2-D electrically large scattering problems.