Decoupling between two planar microstrip lines

A numerical analysis of a two-conductor microstrip transmission line with a rectangular notch in the dielectric between two conducting strips is presented. Three media integral equations are derived and are solved for the charge distributions. The decoupling between such two-conductor microstrip transmission lines is investigated. It is found that the coupling between two conducting lines can be reduced significantly by removing dielectric material between the lines that have a rectangular shape. For the best decoupling, the width should be as wide as possible between the conducting lines, but the depth will have an optimum somewhere in the base dielectric substrate.<>