Surface electric fields of multi-layered medium Green´s functions and the calculation of impedance matrix elements of microstrip structures

The electric fields of the spatial Green´s functions at the interfaces of a multi-layered medium are calculated by integrating along the Sommerfeld integration path. For the case when both sources and field points are on the same interface of two different dielectrics, convergence of the Sommerfeld integrals can be facilitated by higher-order asymptotic extractions. The results are illustrated for distance ranges from 0.02 free-space wavelengths to 1.5 free-space wavelengths. The tabulated electric field Green´s functions are then used to compute the impedance matrix elements of multi-layered microstrip structures in the spatial domain