Rectangular Bars Coupled Through a Finite-Thickness Slot

A rigorous new solution, based on fringing capacitances and conformal mapping, is presented for the coupling problem in the parallel-coupled TEM transmission-line structure formed by two rectanguIar bars coupled through a rectangular slot, cut Iongitudinatly in a finite-thickness ground plane. The conformal mapping solution is summarized in Appendix I and is based on the procedure published by Getsinger [1]. Graphs of the capacitances needed to calculate the coupling for a given physicat geometry, without solving the complicated equations associated with the theoretical solution, are also presented. A measurement procedure and experimental results are presented which verify the accuracy of the theoretical coupling data.