Originally Posted by
dead_pan
To my untrained eye the design looks a bit muddled, also those angly surfaces can't be great for stealth.
They are actually just what you need. A straight or flat surface will reflect EM energy in a straight line as a function of the arrival/closure angle. That means quite tightly focused reflected energy with a narrow Field of View which is harder to detect. With curved surfaces the reflected energy goes off at multiple angles, so although at a lower energy level due to the wider dispersion, you have a much wider capture aperture and greater detection Field of View. It's like the difference between a shaving mirror or a disco ball*.
*Disco ball is what we looked at before cell phones were invented.