Measured equation of invariance with non-uniformly distributed line sources as metrons

In the paper, δ functions are employed as simple yet effective metrons to generate measured equation of invariance (MEI) coefficients in the MEI method. Compared with the widely used sinusoidal functions, δ functions greatly reduce the time for the computing of measuring functions and alleviate the ill-conditioning phenomenon of the matrix equations for the determination of MEI coefficients, hence enabling one to interrelate more nodes in the MEI. In this way, the accuracy of the solutions for electrically large scatterers can be improved progressively. It is also found that non-uniformly distributed δ metrons produce more accurate and stable results compared to uniformly distributed metrons. Numerical results for two-dimensional scattering problems are presented to show the accuracy and efficiency of the proposed method.