On the computation of electromagnetic field components from a transmission line: theory and application

Two programs, EMIDIF and EMIDIP, for computing emissions in near and far field from simple thin wire structures are described. An example applied to digital circuits is given and results obtained with these two programs are compared with those obtained with MININEC. Results are in good agreement. EMIDIF code is useful when one knows the currents at the ends of the lines, calculated by transmission line models. EMIDIP is useful when one knows the distribution along the conductors. EMIDIP allows one to predict both differential and common mode radiated emissions. Common mode current is very difficult to calculate without taking into account displacement current. However, in practical situations, common mode current can be measured by a current probe and the complete field can be calculated