Chaff finds are mainly used in electromagnetic countermeasures. A cloud of chaff is an artificial target made up of a bunch of small thin metallized glass fiber or wire. Chaff consists of thin dipole elements cut to resonate at radar frequencies. Chaff Clouds are dispensed in the air through the chaff cartridge on aircrafts. Chaff Cloud masks the real target return signal therefore, the detection of target become more complicated. The reflected signal from the chaff cloud disturbs the opponent’s radar system and creates a false signature in the enemy radar. Because of high RCS signature, after launching a chaff cloud, the incoming missile tends to track on the chaff. The aircraft can then perform a fast, sharp maneuver, deviating from the missile path.
Radar Cross Section (RCS) is defined as the area a target would have to occupy to produce the amount of reflected power that is detected back at the radar, and is classified according to the types of mono-static or bi-static radars. Most RCS measurements of interest are of monostatic case, for which the radar transmitter and receiver are sensibly at the same point in space. For the bistatic case, the transmitter and receiver are separated. In RCS calculation the radar target scattering data is collected.
The calculation of electromagnetic scattering by a chaff cloud is complex and no exact theory is currently available for calculation of all the phenomena observed. Several technique has been proposed for chaff cloud modeling [1, 2]. In conventional method, usually the RCS of a unitary strip is computed and later the statistics of a chaff cloud are taken into consideration, in order to evaluate its global electromagnetic characteristics. One disadvantage of this computation approach is, it does not consider the coupling among adjacent strips and does not include the target in the scenario.
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