Chaff, originally called Window or Düppel, is a radar countermeasure involving the dispersal of thin strips of aluminium, metallized glass fiber, or plastic. Dispersed chaff produces a large radar cross section intended to blind or disrupt radar systems.
Modern US Navy RR-144 (top) and RR-129 (bottom) chaff countermeasures and containers. Note how the strips of the RR-129 chaff (bottom) are of different widths, while those of the RR-144 (top) are all the same width. The RR-144 is designed to prevent interference with civil ATC radar systems.
A Lancaster dropping chaff (the crescent-shaped white cloud on the left of the picture) over Essen during a thousand-bomber raid
Two forms of RAF "Window" radar countermeasure: chopped aluminium wire and paper backed with aluminium foil
The effect of chaff on the display of a Würzburg Riese radar. The effect of jamming appears in the left "jagged" half of the circular ring, contrasting with the normal "smooth" (unjammed) display on the right half of the circle with a real target at the 3 o'clock position – on the jammed left side, the real target "blip" would have been indistinguishable from the jamming.
Radar jamming and deception
Radar jamming and deception is a form of electronic countermeasures that intentionally sends out radio frequency signals to interfere with the operation of radar by saturating its receiver with noise or false information. Concepts that blanket the radar with signals so its display cannot be read are normally known as jamming, while systems that produce confusing or contradictory signals are known as deception, but it is also common for all such systems to be referred to as jamming.
German Luftwaffe Tornado ECR (Electronic Combat / Reconnaissance). This fighter specializes in electronic warfare.
