How can a stealth fighter be invisible?
A stealth fighter is not really invisible; it is just that we cannot detect its presence with radar. Why does it have such a characteristic? Let us explain it with the operation of radar. The so-called “radar detection” refers to a situation in which electromagnetic waves, being emitted by an observer, is reflected to its original direction by the metal surface of an aircraft and then received by the observer (Fig. 1). The observer can rely on the time difference from emission to reception to locate the enemy fighter. Traditional aircrafts usually have a curved surface in order to minimize air resistance in flight. Therefore, electromagnetic waves impinged in any direction will be partly reflected to their original direction, leading to a large signal on the radar detector. Some modern stealth fighters are structured with a large number of faceted flat surfaces (Fig. 2), and thus electromagnetic waves will not be reflected effectively to their original direction. Apart from that, the m
