# Aspect Angles in 3D (Radar Cross Sectional Area)

a bit confused with regards to the whole term aspect angle in a 3D planar case. Most examples that I searched online involved either a 2D plane or a stationary object. Let say the black circle denotes a ball that flies in a projectile motion as shown. In this case, is the aspect angle always 180 degrees since the angle between the compass direction that the slope/ball faces and what the radar faces is 180 degrees? (i.e. radar is seeing the ball coming directly towards it in a projectile motion?

In this case, will the RCS remain constant? I've seen some example of RCS vs Aspect Angle graphs. While I know RCS is only determined by other factors, does having the same aspect angle in this case denotes the same RCS throughout the whole duration of the projectile motion?

Also, case #2 (to double check on my aspect angle concept): Viewing from the top, let say another ball is thrown nearer to the radar as depicted in the projectile motion (from top to bottom). In this case, if the ball is somewhere in the middle of the motion, will that be the aspect angle between the radar and the ball that I have drawn out?

Thanks!

• What is the definition of aspect angle? Does it not involve the orientation of the body apart from its relative location to the observer? Please add details regarding the formulae that you are using. Please use the edit option below the question.
– AJN
Jan 27, 2022 at 12:01
• Using this definition: The aspect angle θ is defined as the angle between the major axis of the target (heading direction) and the radar LOS. There isn't any formula per say, just checking my definitions whether they are correct. As for orientation, what does that exactly mean?
– THW
Jan 28, 2022 at 1:45
• How can you establish major axis on a ball which is a sphere? Are you constructing the major axis from the velocity vector? I don't that it is correct. Perhaps you should provide a few links to the sources which you have referred so far.
– AJN
Jan 28, 2022 at 11:55