Application of Kummer's transformation in fast computation of mixed potential green's function for cylindrically stratified structure

Computation of spatial domain Green's function for cylindrically stratified structure is usually a very challenging and time consuming task, because not only a Sommerfeld integral on k/sub z/ complex plane is involved, but also the cylindrical eigen mode expansion will lead to a slow convergent series. Furthermore, numerical overflow and underflow will easily occur when we evaluate large order cylindrical eigen mode. This is a typical problem when the radius of the cylinder is of several times of wavelength and the evaluation of large order cylindrical eigen mode is necessary. A method using Kummer's transformation to speed up the computation of mixed potential spatial domain Green's functions for cylindrically stratified media has been developed for solving mixed potential integral equation.