Accession Number : ADA320245

Title :   Wideband Electromagnetic Scattering/Analysis Program. A Caustic Corrected Uniform Geometrical Theory of Diffraction for Evaluating High Frequency Electromagnetic Fields Near the Cusp of the Caustic Caused by the Curvature of an Edge.

Descriptive Note : Interim rept. 1 Jan-31 May 94,

Corporate Author : OHIO STATE UNIV COLUMBUS ELECTROSCIENCE LAB

Personal Author(s) : Meloling, J. H. ; Marhefka, R. J.

PDF Url : ADA320245

Report Date : OCT 1994

Pagination or Media Count : 274

Abstract : An improvement to the Uniform Geometrical Theory of Diffraction (UTD) is developed for determining the high frequency electromagnetic fields near the caustic caused by the curvature of an edge. Although the classic UTD correctly compensates for the discontinuities of the Geometrical Optics fields, it does not correct for caustics created by a curved edge. In particular, for a flat plate with a curved edge that is symmetric about a line, a caustic will occur for a source or observer, when two or more diffraction points merge. This work is devoted to the development of a caustic corrected UTD solution. This means that uniform asymptotic techniques are used to obtain a solution that reduces to the classical UTD result away from, is bounded near, and reduces to the known result at the caustic. Results are calculated for several geometries and compared with the Method of Moments. The results are shown to be in excellent agreement in the caustic regions and smoothly reduce to the UTD away from the caustic regions. Finally, the resulting solution is a very fast and efficient way of computing the high frequency field diffracted by a curved edge due to its ray optical nature.

Descriptors :   *ELECTROMAGNETIC FIELDS, *DIFFRACTION ANALYSIS, MATHEMATICAL MODELS, FOURIER TRANSFORMATION, POLARIZATION, HIGH FREQUENCY, ELECTROMAGNETIC SCATTERING, ASYMPTOTIC SERIES, REFLECTIVITY, METHOD OF MOMENTS, PLANE WAVES, FLAT PLATE MODELS, CURVES(GEOMETRY).

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE