Application of the characteristic Green´s function technique in closed-form derivation of spatial Green´s function of finite dielectric structures

A closed-form spatial Green´s function for finite dielectric structures is derived by using a combination of the characteristic Green´s function (CGF) and rational function fitting method (RFFM). CGF-RFFM represents both of the discrete and continuous spectrum contributions efficiently by using the modified VECTFIT algorithm. To obtain more accurate results, reflection coefficient correction due to the surface waves (SWs) incident on the the end-facet is considered. The main advantage of this method lies in its speed as well as accuracy. Excellent agreements with the rigorous method of moments (MoM) are shown in several examples.