Chaff (countermeasure)

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Chaff" countermeasure – news · newspapers · books · scholar · JSTOR (January 2024) (Learn how and when to remove this message)

Chaff, originally called Window^[1] or Düppel, is a radar countermeasure involving the dispersal of thin strips of aluminium, metallized glass fiber, or plastic.^[2] Dispersed chaff produces a large radar cross section intended to blind or disrupt radar systems.^[3]

Modern military forces use chaff to distract active radar homing missiles from their targets. Military aircraft and warships can be equipped with chaff dispensing systems for self-defense. During its midcourse phase, an intercontinental ballistic missile may release chaff along with its other penetration aids.

Contemporary radar systems can distinguish chaff from legitimate targets by measuring the doppler effect;^[4] chaff quickly loses speed after leaving an aircraft, and the resulting shift in wavelength of the radar return can be measured. To counter this, a chaff cloud can be illuminated by the defending vehicle with a doppler-corrected frequency. This is known as JAFF (jammer plus chaff) or CHILL (chaff-illuminated).^[5]