The paper deals with the computer-aided tomographic reconstruction of radar images of objects behind opaque dielectric walls that are illuminated by microwave radiation emerging from moving ultrawideband (UWB) radars. Tomographic techniques such as filtered backprojections are used here, in conjunction with some available electromagnetic computational codes such as X-Patch, to create the desired target images. The use of UWB radars to penetrate through the walls and image the objects behind them is novel and of obvious desirability. It is only possible if the walls are not too thick and not too lossy. In the present work, several wall types of different dielectric compositions and thicknesses are used to simulate a room that encloses two human targets placed at specified locations. The UWB radar moves along the room's front wall in a straight path with its beams directed normal to the wall and pointing towards its interior. Some basic principles of classical tomography are reviewed, and the reconstruction process via the X-Patch computational code and present-day backprojection techniques is completed for all the walls and targets here considered. This simulation demonstrates that under the specified conditions, the reconstruction of the radar images of the two humans is clearly achievable in all but in very adverse conditions. Furthermore, the dimensions and wall characteristics of the rooms can be estimated from the resulting radar images.