Electromagnetic scattering by large and complex structures with surface equivalence principle algorithm

Abstract

This paper discusses the application of the (surface) equivalence principle algorithm (EPA) in solving electromagnetic scattering by multiple metallic and dielectric objects of arbitrary shape. The EPA introduced earlier by Li, Chew and Jiang is generalized for an arbitrary number of metallic and dielectric scatterers and for an arbitrary surface integral equation formulation. The properties of the algorithm are investigated and discussed in detail. The major benefit of EPA is that it essentially improves the condition number of the system matrix. This is crucial when the matrix equation is solved iteratively, e.g. with Krylov subspace methods. The conditioning of the matrix equation due to EPA is found to be almost independent of the surface integral equation formulation. This is a significant difference compared to the traditional method of moments and fast multipole methods where the conditioning of the matrix depends strongly on the underlying surface integral equation formulation. Another result is that the original EPA can lead to a loss of accuracy if the equivalence surfaces are close to each other or close to the original targets. As a remedy for this problem a novel EPA, called tangential EPA (T-EPA), is developed. The developed algorithm is applied to solve electromagnetic scattering by a relative large number of (isolated) metallic and homogeneous dielectric objects and to efficiently model complex metamaterial structures.