A boundary integral method for numerical computation of radar cross section of 3D targets using hybrid BEM/FEM with edge elements

Poljak

Numerical Meth Engineering

2021

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Over recent decades coupled MoM/FEM formulation emerged as dominant method for solving EM scattering problems over inhomogeneous domains. Initial efforts on coupling of edge element BEM with edge element FEM have lost momentum and somehow disappeared from recent literature, possibly because of mathematical and other issues. This article, however, presents correct coupling of edge element BEM with edge element FEM. Such coupling is convenient because edge basis functions are used for modeling both the surface and the interior of the problem. We show that singularity extraction is simpler when compared with singularity extraction in MoM/FEM. Because BEM part of edge element BEM/FEM formulation uses simpler Green's function, the method is easier to implement than MoM/FEM which uses Dyadic Green's functions. The accuracy of the method is demonstrated by comparison with Mie series and with MoM/FEM and MoM/VSIE methods. Convergence of the method with respect to number of surface and interior edges was investigated by comparing 20 computational models with Mie series. Computational results suggest that edge‐element BEM/FEM performs well for scattering problems involving objects with sharp corners. Finally, the ability of the method to cope with relatively large number of elements was demonstrated on the example of human head illuminated by 3.5 GHz EM plane wave.

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Section: Test Cases and Validation Of The Methodsmentioning

confidence: 99%

“…By solving matrix equation shown in Figure 3 we obtain edge element coefficients for both electric and magnetic field on surface

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Section: Coupling Of Edge Element Bem With Edge Element Femmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the edge element boundary element method/finite element method coupling for time harmonic electromagnetic scattering problems

Poljak

Numerical Meth Engineering

2021

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“…Standard near-to-far field transformation (NTFFT) is a computationally cumbersome procedure [13]. To circumvent this, the approach based on [14] is applied to compute the far field and RCS. The method is described in Section 3, and it allows rapid computation of RCS directly from edge element coefficients provided by near field computation.…”

Section: Introductionmentioning

confidence: 99%

On the Application of Hybrid Bem/Fem for Inhomogeneous Electromagnetic Scattering From Small Maritime Targets

Poljak

WIT Transactions on Engineering Sciences

2021

From the standpoint of detectability of small maritime objects by a ship's radar system, the radar cross section (RCS) of a maritime object is a key parameter that determines the detectability of an object. When a vessel navigates in narrow channels and in areas with high sea traffic density, the ability to detect small maritime targets such as buoys and inflatable rubber boats is crucial for maritime safety. However, it is difficult to measure the radar cross section of such maritime objects in environments such as laboratory or in a field test not only due to object size, but also due to the fact that these objects are partially submerged into seawater. In such situations, the most effective approach is to apply numerical methods for electromagnetic scattering from inhomogeneous objects in order to predict the RCS of a maritime object. Though approaches to RCS prediction are diverse, one of the most sophisticated, namely, the hybrid numerical method based on combination of boundary and finite elements is applied in this work. This hybrid numerical method first computes near electromagnetic field on the surface of the scatterer, followed by a particular technique developed by the authors to compute the radar cross section of small maritime targets from these near field values. The accuracy of the approach is discussed and some illustrative computational examples of RCS calculations are given.

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Stochastic dosimetry of a three compartment head model

Šušnjara

Engineering Analysis with Boundary Elements

et al. 2020