Efficient numerical computation of the spectral transverse dyadic Green's function in stratified anisotropic media

Several new ideas are provided for computing the spectral transverse dyadic Green's function (STDGF) of a stratified anisotropic medium in an accurate and efficient way. A modified version of the equivalent boundary method is developed which makes it possible to compute the asymptotic values of the aforementioned. STDGF without employing exponential terms. This new technique for the computation of the STDGF of a stratified anisotropic medium has more numerical stability than the other techniques proposed so far, in which the use of exponential terms for the computation of the STDGF in all the range of variation of the spectral variables unavoidably leads to numerical problems for high values of the spectral variables. Also in this paper, it is shown how a two-step interpolation approach can be used for obtaining simple closed-form expressions of the STDGF of a stratified anisotropic medium in wide ranges of the spectral variables. It is expected that the use of this interpolation approach will introduce important CPU time savings in the spectral domain analysis of planar microwave circuits and printed antennas, where the STDGF of the substrate has to be calculated a large number of times.