Context: Defence Research and Development Organisation (DRDO) has developed an Advanced
Chaff Technology to safeguard the naval ships against enemy missile attack.
Analysis
• Chaff is a passive expendable electronic countermeasure technology used worldwide to protect
naval ships from enemy’s radar and Radio Frequency (RF) missile seekers.
• Chaff is an artificial cloud consisting of a large number of tiny metallic reflecting strips that
create strong echoes over a large area to mask the presence of real target echoes or to create
confusion.
• The importance of this development lies in the fact that very less quantity of chaff material
deployed in the air acts as decoy to deflect enemy’s missiles for safety of the ships.
o Decoy is any deceptive device used to draw an enemy awHow do modern military aircrafts save themselves from antiaircraft missiles?
• The main threats to modern military aircraft are antiaircraft missiles, which travel faster and
maneuver better than the best jet fighters.
• Heat-seeking missiles are designed to follow heat sources such as the jet exhaust of a modern
aircraft.
o To elude these missiles, a jet may release active decoys called flares, which are tubes
containing magnesium that burn with an intense white heat.
o Because flares initially burn hotter than jet exhaust, they may confuse the missile by
offering it several hot targets, giving the aircraft a chance to escape.
• Radar-guided missiles, another form of antiaircraft missiles, use radar to locate their targets.
o While flares are useless against this technology, radar is vulnerable to a type of active decoy
known as chaff, which consists of tiny strips of aluminum or zinc that the aircraft releases in
large bunches.
o These metallic clouds appear as separate targets to the missile’s radar and ideally confuse
the missile, thus permitting the aircraft to escape.
How do radar sensors work?
• The integrated antenna of the radar sensor emits a high-frequency signal.
• The sensor receives the signal when it is reflected back from an object.
• The time difference between transmitting and receiving determines the distance between the
object and the sensor.
• Every frequency has unique properties. The frequency determines the type of reflection and
whether there is any reflection at all.
o A 5 GHz radar allows you to easily detect rain clouds at very large distances.
o In contrast, a 60 GHz radar will pass through rain clouds and thus not recognize the clouds.
But the signal will reflect off aircraft or other objects.
• In contrast to radio station signals, radio signals from a radar sensor are reflected from
buildings and liquids.
o This is because of the higher radar frequency. The higher the frequency, the less
impenetrable walls (and other objects) become.
The perfect alternative to ultrasound and laser
• Besides radar, you can also measure distances with ultrasonic sensors and lasers.
• Every technology has its own pros and consay from a more important targetFor example, ultrasonic signals cannot pass through materials, such as plastic and
plants. Laser signals are also blocked by such materials. Moreover, sound can be shifted by
wind.
• In contrast to sound and light signals, radar signals from a radio can make measurements
through most materials. The signal is only impeded by metal objects.
o Thanks to these properties, radar is suitable for agricultural machinery and can measure
distances to the ground without the measurement results being affected by crops