Time Domain Measurement of Near Field Emissions from Complex PCBs

This paper discusses how the measurements of the near-field emissions in the time domain can be used to characterize the broadband emissions from complex sources such as multifunctional Printed Circuit Boards (PCBs). The near fields, transverse to the measurement surface, are sufficient to characterise the radiator provided the surface contains all the significant fields. For time domain measurements, the field probe is calibrated over a broad bandwidth for both amplitude and phase to provide the probe impulse response. A suitable digital filter applied with the same probe impulse response to extract the time domain magnetic field data from the probe output voltage. Results show that good agreement in the can be obtained. The measured near fields can then be used to create an equivalent model of the PCB which can be used to predict the emissions in the far field or in any environment. In this work the objective is to create an equivalent time dependent dipole array model of the DUT.