Incremental Fringe Formulation for a Complex Source Point Beam Expansion

Abstract

An Incremental Fringe Formulation (IFF) for the scattering by large metallic objects illuminated by electromagnetic Complex Source Points (CSPs) is presented. This formulation has two main advantages. First, it improves the accuracy of Physical Optics (PO) computations by removing spurious scattered field contributions and, at the same time, substituting them with more accurate Incremental Theory of Diffraction field contributions. Second, it reduces the complexity of PO computations because it is applicable to arbitrary illuminating fields represented in terms of a CSP beam expansion. The advantage of using CSPs is mainly due to their beam-like properties: truncation of negligible beams lowers the computational burden in the determination of the solution. Explicit dyadic expressions of incremental fringe coefficients are derived for wedgeshaped configurations. Comparisons between the proposed method, PO and the Method of Moments (MoM) are provided.

An Efficient Numerical Contour Deformation Method for Calculating Electromagnetic Scattered Fields From 3-D Convex Scatterers

“…However, due to the inaccurate approximation of the PO current around the transition region and in the shadow region of the scatterer, the scattered fields loose accuracy with the observation point located in these regions. To improve the accuracy of the scattered field, researchers proposed the incremental diffraction techniques, for instance, the physical theory of diffraction (PTD), the ILDC [6,7,[10][11][12][13][14] and the incremental theory of diffraction (ITD) [3][4][5]. Based on the incremental theory of diffraction localization process for the canonical problems, the incremental field contributions are presented by a general procedure in [3].…”

Modified Edge Representation (MER) Consisting of Keller’s Diffraction Coefficients With Weighted Fringe Waves and Its Localization for Evaluation of Corner Diffraction

“…First, MER utilizes the diffraction law not in the spectral but in spatial domain for extending the definition to general edge points. Second, MER directly brings about the uniform total fields while ITD singularities are canceled out in the form of fringe wave (FW) like physical theory of diffraction (PTD) [17], [18]. This paper investigates the accuracy of MER EECs for flat plates in detail by comparing with method of moments (MoM), uniform theory of diffraction (UTD) [2], and physical optics (PO) [19] for dipole illumination.…”

Effective Fringe Equivalent Currents Expressions

“…However, the second-order EEC is hard to be applied to complex targets. Recently, an incremental fringe formulation was presented for the field scattered by edges when illuminated by complex source points [5].…”