Radiation from differential printed traces

The paper presents an investigation of radiation from a pair of printed traces carrying differential signals. Both microstrip and partial stripline type traces are examined. The effect of phase shift arising from skew between the two differential signals is evaluated and is found to compromise the radiation reduction property. Furthermore, it is shown that closely spaced differential traces can result in a "common mode" component of the current in the partial stripline case. For this reason, the shielding advantage of burying a differential trace is not as significant as that for a single ended trace. This analysis is based on a mixed potential integral equation technique combined with a multi-port network formulation. Numerical results are presented and discussed