AN HYBRID MODEL FOR THE EVALUATION OF THE FULL-WAVE FAR-FIELD RADIATED EMISSION FROM PCB TRACES

Abstract

The paper deals with the evaluation of the far-fleld radiated emissions from high-speed interconnects when the frequencies are such that the distribution of the currents along the traces is no longer of TEM-type. Instead of a computationally expensive numerical full-wave model, here a generalized transmission line model is used to obtain the current distributions. This full-wave transmission line model is derived from an integral formulation and is here extended to include in e-cient way the layered media Green's Functions. The proposed tool is successfully benchmarked to references given in literature and case-studies of practical interest are carried out, referring to a coupled microstrip, driven either by difierential and common mode currents. This analysis highlights the existence of a transition range where the error made by evaluating the emission using the classical transmission line current distribution is still negligible. Here a rule of thumb is derived which provides a simple criterion to estimate this extension of the range of validity of the classical transmission line.