ITD Double-Edge Diffraction for Complex Source Beam Illumination

Toccafondi, A.; Canta, Stefano M.; Erricolo, Danilo

doi:10.1109/tap.2013.2244553

Cited by 3 publications

(1 citation statement)

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“…In the above discussion, two kinds of weighting functions consisting of the Fresnel zone number (FZN) [19] are introduced with different objectives. The first one is for correcting the errors in FW components in specific angle of grazing incidence, which was also discussed in the alternative way in ITD [20] for the double diffraction mechanism. The second one is for extracting the corner diffraction to demonstrate the validity of MER EECs at general edge points.…”

Section: Introductionmentioning

confidence: 99%

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

Ali

Kohama

Ando

2015

IEEE Trans. Antennas Propagat.

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Equivalent edge currents (EECs) for high-frequency diffraction analysis are intermediate concepts between ray theory and wave optics [physical optics (PO)]. The methods of EEC present some ambiguity in the definition of currents at general edge points, which do not satisfy the diffraction law. Modified edge representation (MER) is a unique concept for a complete definition of EEC with simple and classical Keller-type knife-edge diffraction coefficients. Although singularities in the definition of EEC exist, the line integration of MER EEC results uniform and accurate fields everywhere including geometrical boundaries except for the case of grazing incidence, where reflection and incidence shadow boundaries (RSB and ISB) are close to each other. In this paper, fringe wave (FW) part of MER EEC is modified by introducing the weighting in terms of Fresnel zone number (FZN) distance from the reflection point to improve the accuracy at and near shadow boundaries even in grazing incidence. Next, the corner diffraction, a contribution coming from edge point which does not satisfy the diffraction law, is extracted in MER by introducing another weighting function using the FZN distance from scattering centers on edge. Its remarkable accuracy fully validates MER EECs at general edge points. The dipole wave scattering from flat square and triangular plates are discussed with numerical examples. Index Terms-Corner diffraction, equivalent edge current (EEC), Fresnel zone, geometrical theory of diffraction (GTD), modified edge representation (MER), uniform theory of diffraction (UTD).

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Section: Introductionmentioning

confidence: 99%

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

Ali

Kohama

Ando

2015

IEEE Trans. Antennas Propagat.

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Converging and Diverging Beam Diffraction by a Wedge: A Complex-Source Formulation and Alternative Solutions

Katsav

Heyman

2016

IEEE Trans. Antennas Propagat.

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In a previous publication, the problem of 2D beam diffraction by a wedge has been solved via the complex source (CS) approach. However, the straightforward CS formulation may be applied only when the incident beam is diverging as it hits the edge, but not when it is converging as it hits the wedge. In the present paper, we generalize the CS setup so that it can address both problems. The surprising result is that the CS approach can be applied for the converging beam case, but only if the CS coordinates are defined in specific fashion. We then formulate the angular harmonics and the spectral integral representations for both cases, and also derive for both cases, uniform asymptotic expressions for beam diffraction by a wedge. The validity of the results is verified by calculating the diffracted field via each one of these formulations, and comparing them with yet another approach wherein the field of the incident diverging or converging beam is synthesized using a plane wave integral, and the diffracted field is then calculated via multipole expansion. The overall goal of this research is the derivation of techniques for the analysis of 3D beam diffraction by a cone.

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