Accuracy of Equations for Coupled Slab Lines (Letters)

The determination of the characteristic impedance of coupled slab lines has been a subject of investigation for many years. Following on Frankel´s pioneering work [1], Chisholm obtained art accurate analytical solution for the odd-mode impedance of a pair of coupled slab lines [2]. In 1980, Levy presented Chisholm´s equations, together with those due to McDermott for the even-mode impedance, in a general form suitable for calculation [3]. He also confirmed the accuracy of the equations with an efficient numerical procedure.