This article presents numerical results for the propagation of the electromagnetic field due to a partial discharge in a three-phase power transformer. The results obtained in order to know the waveforms in time and frequency identifying the range where the signal is strongest and make the selection of the type of antenna, geometry and location more optimal to detect PD. As a result, ranges are observed in the signal spectrum where it is strongest and the importance in the orientation of the antenna where the signal has greater influence is demonstrated.