Computation of Sommerfeld integrals via rational function fitting

A new methodology is proposed for the robust computation of the Sommerfeld integrals encountered in evaluating the electromagnetic Green´s function in planar layered media. The key attribute of the proposed methodology is that it yields a closed-form expression for the Green´s function in terms of both spherical waves and cylindrical waves. The former, representing the source and quasi-static terms, provide for the accurate description of the singularity and the near-field physics in the vicinity of the source, while the latter capture correctly the surface wave behavior that dominates in the far field.