Calculation of coupling gap and fringing capacitances in coupled rectangular bars between ground planes

A structure comprising an array of coupled rectangular bars between ground planes, in which it is frequently desired to know the appropriate spacing to realize a given bar-to-bar coupling capacitance per unit length, is considered. The converse problem of finding the coupling capacitance given the spacing was treated by Getsinger (1962) but the results, presented in graphical form, are not easy to incorporate into a computer program. A new analysis which solves the problem directly, in a form capable of being implemented numerically, is presented. An algorithm is given to calculate the fringing capacitances and their distribution.