Electronic Weapons: AESA Evolution Continues


October 8, 2021: An American firm, Raytheon, has developed a new lightweight AESA (Active Electronically Scanned Array) fire control radar for aircraft, ships or ground forces that weighs about 48 kg (110 pounds). This is the lightest and most compact radar of this type developed so far. There are several types of AESA radars with maritime or ground surveillance being the lightest and the fire control models weighing somewhat more because they include more capabilities. The new Raytheon AESA radar is light enough for large UAVs and helicopters.

Maritime surveillance AESA radars of comparable weight have been around for over five years and these enhance the capabilities of UAVs and small aircraft used for maritime surveillance. For example, in 2016 the U.S. Navy selected the Italian Osprey AESA radar for its MQ-8C Fire Scout helicopter UAV. The Osprey radar is lightweight (50 kg/110 pounds) and uses small flat panels on the sides of the aircraft instead of a rotating radar in a dome underneath the aircraft. The three flat panels give the Osprey radar 360-degree coverage of the waters below. Lighter and cheaper versions of the Osprey are available that provide less coverage but all versions of Osprey can detect small boats out to about 160 kilometers.

AESA tech has been around since the 1960s, first as PESA (Passive electronically scanned array) and by the 1980s that had evolved into AESA. Since the 1990s AESA radars have become standard for most new aircraft and upgrades for older aircraft. As AESA systems have gotten smaller and lighter they are showing up more often in UAVs. AESA is more reliable and, increasingly, no more expensive than the older mechanical (a small dish that moves around inside a dome) radar. AESA uses less power and is easier and cheaper to maintain. This makes a more expensive AESA radar cheaper, over its lifetime, than a cheaper (to buy) mechanically scanned radar. AESA radars are more reliable because they have no moving parts, are more compact and use less power than earlier, non-AESA radars.

AESA type radars have been around for a long time, popular mainly for their ability to deal with lots of targets simultaneously, and produce a more accurate picture of what is out there. Initially AESA was also a lot more expensive, and less reliable, than older radar technologies. That gradually changed. And now more uses are being found for AESA, which has developed into more than just an improved radar. AESA radar consists of thousands of tiny radars that can be independently aimed in different directions. An AESA radar made the 1990s E-8 JSTARS ground surveillance aircraft possible, as its AESA radar was able to locate vehicles moving on the ground, just as the later Osprey radar does but with a much heavier and expensive AESA radar. Larger and more powerful AESA radars can provide images of what is on the surface and do it in all weather and at night. This what the E-8 used and subsequent AESA designs also incorporated that, as well as the ability to act as an electronic jammer or a communications device. About a decade ago the MP-RTIP AESA radar for the RQ-4 Global Hawk UAV was developed. This one weighed about twice as much as the Osprey but could detect and identify smaller objects on the ground from high altitudes. As a result, RQ-4 UAVs equipped with AESA gave the air force a choice between extending the life of the E-8 aircraft or replacing them with the UAVs using the new AESA systems. The air force decided to use a larger version of MP-RTIP AESA in current E-8 aircraft as well the original design in RQ-4s.




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