**1.2 Background on the EMC application of the transient EM-NF**

As aforementioned and discussed (Rammal et al. 2009, Jauregui et al. 2010a), the EM-transient analysis is actually important for the immunity predictions in the mixed or analogue-digital components constituting the high-speed electronic boards regarding the eventual radiations of high power electrical circuitry as the case of neighbouring hybrid electric vehicle propulsion systems. To assess such an EMC effect, as reported in (Adada 2007), the electronic circuit designers working on analogue/mixed signal (AMS) subsystems have preferred software tools such as SPICE, while those working on RF/microwave front-end components have tended to manipulate S-parameter frequency-domain design and simulation tools. By cons, currently, the fusion of the both approaches as AMS engineers are required to make further analysis on the critical components is needed by using the adequate EM simulation tools. In this case, we have to elaborate the context of ultra-wide band (UWB). Currently, this topic is one of improvement techniques in the area of EMC application. In this optic, the modelling of mixed component EM-NF emission becomes one of the crucial steps before the implementation process. Therefore, the undesired EMC radiations should be investigated not only in frequency-domain but also in time-domain. For this reason, we propose in this chapter an extraction method enabling to determine the time-domain EM-NF maps from the frequency-dependent data by using the Fourier transform of the 2D data.
