It seems like odd placement for rear radar. This would be analogous to the FOV of front radar, where it can read speeds of distant objects in all lanes and close-up objects right behind it.
Most cars implementing forward or rear cross traffic detection use directional radar on corners. Either front, rear, or all 4 corners like you see in the Audi Q7. The 4 corner solution also allows you to get rid of the center radar in the front and that effectively gives you redundant dual forward radar plus cross-traffic visibility and oncoming traffic discrimination.
It just seems odd to put a center radar in the back. Unless your rear camera view solution is really not gonna work, or you want to implement something like rear-ending-avoidance in the short run.