An Efficient Numerical Approach Combining Finite Element with Integral Methods

We propose a numerical approach that combines both finite elements with volume and boundary integral methods. The boundary integral formulation replaces the far incident field source with a set of monopole and dipole sources, which are in the vicinity of the object and generate an equivalent illumination. Then the electromagnetic interaction between this incident field and the object under test is modeled by finite elements on a much smaller domain. The volume integral formulation is introduced to calculate semi-analytically the total field at any point outside the finite element discretization domain. Numerical results show that this approach speeds up the computation time, reduces the memory consumption, and does not suffer from a lack of accuracy when the source and observation points get more distant from the object, contrary to a pure finite element resolution. The proposed numerical approach is also successfully tested on the Fresnel Institute's microwave measurements.