The examination of new equivalent edge currents in the prediction of high frequency backscattering from flat plates

Abstract

Equivalent edge currents based on the geometrical theory of dilfraction (GTD) have been utilized for the prediction of electromagnetic scattering from edged bodies. These equivalent currents are use Keller’s diffraction coefficient and therefore not valid for arbitrary aspect of observation. More general expressions for equivalent edge currents are later obtained by Michaeli. Those expressions become infinite at certain observation directions. These infinities are later eliminated by the same author for the fringe component of the equivalent currents l)y choosing a skew coordinate system on the half plane to be used for the asymptotic integration. A similar approach is employed here to eliminate the infinities in the physical optics(PO) component of the equivalent edge currents. It is also shown that the radiation from the fringe and PO equivalent currents is unique and yields the GTD field. The fringe and PO equivalent currents are then applied to the backscattering problems from the perfectly conducting square and triangular plates. The higher order interactions between the edges are also included into the analysis. Some improvements are obtained over the previous solutions.