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Fresnel Zone Criterion to Implement Locality in the Method of Moments and POMoM Hybrid Method for the Reduction of Unknowns
Keita ITO Tetsu SHIJO Makoto ANDO
Publication
IEICE TRANSACTIONS on Electronics
Vol.E94C
No.1
pp.7279 Publication Date: 2011/01/01
Online ISSN: 17451353
DOI: 10.1587/transele.E94.C.72
Print ISSN: 09168516 Type of Manuscript: PAPER Category: Electromagnetic Theory Keyword: method of moments, physical optics, geometrical theory of diffraction, hybrid method, radar cross section,
Full Text: PDF(1.7MB)>>
Summary:
Locality of high frequency electromagnetic scattering phenomena is embodied and imported to the Method of Moments (MoM) to reduce computational load. The proposed method solves currents on small areas only around inner and edge stationary phase points (SPPs) on the scatterer surfaces. The range of MoM area is explicitly specified in terms of Fresnel zone number as a function of frequency, source and observer positions. Based upon this criterion, scatterer of arbitrary size and shape can be solved with almost frequency independent number of unknowns. In some special cases like focusing systems, locality disappears and the method reduces to the standard MoM. The hybrid method called POMoM is complementarily introduced to cope with these cases, where Fresnel zone number with analogous but different definition is used. The selective use of LocalMoM and POMoM provides frequency insensitive number of unknowns for general combination of source and observation points. Numerical examples of RCS calculation for two dimensional flat and curved surfaces are presented to demonstrate the accuracy and reduction of unknowns of this method. The Fresnel zone, introduced in the scattering analysis for the first time, is a useful indicator of the locality or the boundary for MoM areas.

