In this paper, we are interested in identifying all areas inside a urban canyon that can be illuminated by a radar in NLOS (non line of sight) configuration. We developed a simple model to identify, according to each canyon configuration, the ground canyon areas illuminated by the radar and also the non illuminated areas. We test the results of our algorithm for a specific canyon. To validate our theoretical results we finally present some measurements that will be performed in the anechoic chamber of ONERA on a scaled urban canyon in the case of far field.