Open your eyes.
The research was carried out in azimuth. Look at your own picture. There it is even indicated by "arrows".
The wing is oriented horizontally. That is, only the wing edge is exposed to radiation. And no matter how you rotate the wing in azimuth, only the edges will be visible.
The fin is oriented vertically. But the studies were also carried out in azimuth. The arrows also show the angle "theta". Therefore, when the fin rotates, not only the edge but also the plane of the fin itself will be visible.
Therefore, if we consider these two similar objects, then only from a zero angle.
You take, albeit similar objects, but differently oriented in space. And equate them.
Do not mislead those reading this topic.
Boeing was one of the first to deal with these issues (1962-1963). Read at least about the Boeing Model 853-21 Quiet Bird.
