Ferrite Bead Simulation in SPICE
With a 1 ampere AC current source in series with the ferrite bead model, the voltage across the ferrite bead at its terminals (including all of the R's, L', and C's) is numerically equal to it's impedance.  Thus plotting that voltage against frequency gives the desired result of ferrite bead impedance vs. frequency which are the plots given in the application note.