Passive infrared sensors can detect the heat of a stealth fighter from eighty kilometers away
Passive infrared search and track systems can identify stealth aircraft from eighty kilometers away by detecting the thermal signature of engine plumes rather than relying on radar reflections.
Infrared Search and Track (IRST) systems bypass traditional stealth technologies by exploiting the laws of thermodynamics rather than electromagnetism. While a stealth fighter like the J-20 may reduce its radar cross-section to a mere 0.01 square meters, it cannot eliminate the 900-Kelvin heat signature generated by its engine plumes. Modern gallium-based sensors detect these thermal emissions at wavelengths between 3 and 5 micrometers, a range where specialized radar-absorbent coatings often fail to mask the aircraft's presence.
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