T. Ozdemir et Jl. Volakis, A COMPARATIVE-STUDY OF AN ABSORBING BOUNDARY-CONDITION AND AN ARTIFICIAL ABSORBER FOR TRUNCATING FINITE-ELEMENT MESHES, Radio science, 29(5), 1994, pp. 1255-1263
The type of mesh termination used in the context of finite element for
mulations plays a major role on the efficiency and accuracy of the fie
ld solution. In this work we evaluate the performance of an absorbing
boundary condition and an artificial absorber (a new concept) for term
inating the finite element mesh. This analysis is done in connection w
ith the problem of scattering by a finite slot array in a thick ground
plane. The two approximate mesh truncation schemes are compared with
the exact finite element - boundary integral (FEM-BI) method in terms
of accuracy and efficiency. It is demonstrated that both approximate t
runcation schemes yield reasonably accurate results even when the mesh
is extended only 0.3 wavelengths away from the array aperture. Howeve
r, the artificial absorber termination method leads to a substantially
more efficient solution. Moreover, it is shown that the FEM-BI method
remains quite competitive with the FEM-artificial absorber method whe
n the fast Fourier transform is used far computing the matrix-Vector p
roducts in the iterative solution algorithm. These conclusions are ind
eed surprising and of major importance in electromagnetic simulations
based on the finite element method.