RCS measurements on dihedral corner reflectors have been conducted in the large anechoic chamber located at FOI in Linköping. The results have been used to generate ISAR images. The images exhibit hot spots that are located behind the dihedrals. The question is : what is the origin of those hot spots? This report will present ISAR-images of the 80, 90 and 100 degrees dihedrals. In addition the report presents a short analysis of the images with some scattering phenomena explanations of what can be the cause of the origin hot spots.