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Mensaje: <blockquote data-quote="SuperEtendard" data-source="post: 115827" data-attributes="member: 128">Y aca tenemos un comentario muy interesante...sera verdad<img src="/foros/styles/default/xenforo/smilies/biggrin.png"  class="smilie" loading="lazy" alt=":D" title="Big Grin    :D" data-shortname=":D" /> Rafale may be using active radar cancellationtransmitting an out of phase return signalAccording to the article by Bill Sweetman, French Rafael fighter may be using the so-called active cancellation technique to remain undetected by enemy radars. This technique is a special type of "stealthy" ECM based on the principle of wave superposition. According to the article, Rafael has two antennas separated by the length of the aircraft. The antennas emit electromagnetic waves half a wevelength out of phase with the reflected radar signal, thus effectively reducing its intensity, making the aircraft virtually disappear from the radar's screen. Active cancellation is a highly advanced and extremely complex process. This method is not known to be used on any military aircraft, though there were speculations that Russians may be using this technique on their S-37 and possibly MiG 1.42 prototype fighters. Also it is believed that the Northrop Grumman ZSR-63 defensive aids equipment installed on B-2 bombers may be using active cancellation. Just how complicated it is to cancel a reflected radar signal can be seens from the fact that the original incoming signal from the radar will be reflected from many spots on the aircraft's body. Each spot will produce an individual reflection with its own, often unique, amplitude and phase. The amplitude of the reflection (high amplitude means that the relection would be easier to pick up than the one with lower amplitude) would depend on many factors, such as incident angle, particular type of material, geometrical form of a certain location on the aircraft's body that produced the reflectio and some other factors. The phase shift will be dictated by the wavelength of the radar signal and the location (and geometrical form) of the particular spot that produced the reflection in question. The return signal, picked up by the radar, would look somewhat chaotic, consisting of background noise and "spikes". Background noise is produced by ionization levels of atmosphere, particular atmospheric conditions affecting scattering of electromagnetic waves of a given frequency, secondary reflections (weak signals). The "spikes" are produced by the strong reflections off the certain parts of the aircraftof a particular design. These "spikes" is, presumably, the main target for active cancellation system. By removing these "spikes" from the radar screen the aircraftmay blend in with the background noise, which is normally ignored by the radar operators. It is important to understand, however, that in case of an effective active cancellation system we are dealing with an immensly complicated issue. Something that can be popularly explained with a single wave sinusoidal signal will become progressively more complex in real life situations.<img src="/foros/styles/default/xenforo/smilies/eek.png"  class="smilie" loading="lazy" alt=":eek:" title="Eek!    :eek:" data-shortname=":eek:" /> <img src="/foros/styles/default/xenforo/smilies/biggrin.png"  class="smilie" loading="lazy" alt=":D" title="Big Grin    :D" data-shortname=":D" /> <img src="https://www.smiley-lol.com/smiley/look-beaute/lunetchapeau.gif"  class="smilie" loading="lazy" alt=":cool:" title="Cool    :cool:" data-shortname=":cool:" /> Saludos</blockquote>

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