Two methods for the calculation of internal responses of shielded cables submitted to an external impulse electromagnetic field are analyzed. One is the classical frequency-domain approach, the second is a new mixed frequency-time-domain model, which uses a link to a well-known transient analysis code. This last feature makes possible the application of the second model to complex networks with several branches. In both models, measured values of the cable transfer impedance values have been used. The comparison between internal currents and voltages calculated with both models and measurements using an EMP simulator shows a reasonable good agreement. These comparisons validate the analyzed models and in particular the new combined frequency-time domain approach