A Solution to the 3-Conductor Mapping Problem with Application to Planar Lines and Couplers

A technique is described by which conventional conformal mapping can be extended to analyze some transmission-line configurations which cannot be reduced by symmetry to less than 3 separate conductors. Asymmetrical coupled stripline and the 4-center-strip CPW coupler are used as examples of the technique; calculated results are compared with those found by other methods. A variational advantage is shown for the 4-strip coupler.