IMPROVED IMPEDANCE MATRIX LOCALIZATION METHOD

Moment method calculations have the well-known limitations of requiring excessive storage and execution times for even modestly large electromagnetics problems. The impedance matrix localization (IML) method was introduced as a modification to standard moment method calculations which eases these limitations. It utilizes a matrix transformation which effectively changes the basis (testing) functions into ones resembling traveling waves. An improved method is presented here which uses an orthogonal transformation which generates standing-wave-like basis functions. Remarkable improvements are achieved in the numerical stability of the method and in its compatibility with iterative solvers. Furthermore, the correspondence of the large elements in this matrix to GTD terms is strengthened, as is the possibility of further increasing the speed of iterative solutions by constructing preconditioners based on the pattern of nonzero matrix elements.