Broadband Spectral Numerical Green's Function for Electromagnetic Analysis of Inhomogeneous Objects

In this letter, we present a novel and efficient broadband spectral numerical Green's function (S-NGF) for inhomogeneous region. The proposed S-NGF is formulated in terms of the matrices that are obtained by the finite-element method (FEM). By performing modal analysis to FEM matrices, the proposed S-NGF is encapsulated by a series of resonant solenoidal modes where the operating frequency is embedded in the expansion coefficients. Besides, the convergence of the series of resonant solenoidal modes can be greatly accelerated by performing an extraction at one low wavenumber. The S-NGF can be rapidly reconstructed at different frequencies when it is integrated into the surface integral equation for inhomogeneous object modeling. The proposed algorithm is easy to implement, and well suited for the design and optimization of inhomogeneous electromagnetic structures, where fast solutions at massive frequencies are called for. The numerical examples demonstrate the efficiency and accuracy of the proposed scheme.