Characterisation of radiated fields from PCBs in the time domain

In this paper, a method for representing electromagnetic emissions from a printed circuit board (PCB) using an equivalent dipole model deduced from time domain near-field scanning magnetic field measurements is proposed. The basic idea is to replace the PCB with a set of infinitesimal dipoles that generate the same radiated fields. Parameters of the time dependent equivalent dipoles are determined by directly fitting to the measured magnetic near fields. A simulation of a basic test structure is used to demonstrate the principle and accuracy of the approach. The scanning process is then demonstrated through simulation although it is readily applicable experimentally.