A Universal Overlay for Surface Impedance Calculations for Composite Conductors

Surface impedance calculations for composite conducting surfaces made of two different metals can be made amenable to a universal graphical solution. This is in the form of an overlay to be superimposed on the reflection coefficient plane and is therefore useful in conjunction with either the Smith Chart or the "Zeta-Theta" Chart. An example is given of a composite conductor consisting of a thin nickel interfacing layer underlying a thick layer of gold, such as might be found in the construction of microstrip circuit elements.