In this paper a through the wall radar imaging (TWRI) system based on a step frequency radar is presented. The radar equation is used for assessing the system power budget and two algorithms, namely the delay and sum (DAS) and the range migration (RM) are used for the scenario reconstruction. The achieved results evidence the strong dependence of the radar-re-ceived power on the wall losses. A frequency of 4 GHz seems to be the maximum allowable for practical TWRI systems. A scenario with obstacles placed in visibility of the radar and another with a wall between the radar and the obstacles have been realized. For the first scenario, the DAS algorithm provided better results with respect to RM but with longer processing times. In the second case, only the DAS algorithm was implemented that was able to cor-rectly locate the obstacles.