New expressions for equivalent edge currents

Abstract

It is known that the results of the incremental length diffraction coefficients (ILDC) (Mitzner 1974) and the method of equivalent edge currents (MEC) (Michaeli 1984) differ by terms due to the physical optics (PO) current. These PO components become infinite for certain aspects of observation and illumination, by the extraction of the PO contribution from MEC. ILDC, unlike MEC, predicts finite currents for certain directions of observation. However, as already observed by Mitzner, ILDC also displays infinities for certain combinations of observation and incidence directions, though the range of singular aspects is reduced in comparison with MEC. Michaeli (1986) derived a set of expressions for the fringe current components of the equivalent edge currents, those expressions are finite for all aspects of illumination and observation, except for the Ufuntsev singularity. However, for certain non-singular aspects of the ILDC expressions, there is a wide divergence between Michaeli's (1986) results and Mitzner's results. In this paper, new expressions are derived for the fringe current components of equivalent edge currents, which are advantageous over those of Mitzner and Michaeli in both accuracy and versatility. A numerical example of the bistatic RCS of a square plate is given.