AESA (Active Electronically Scanned Array) radars are becoming standard equipment in modern warplanes, for those that can afford them, and appreciate their power and versatility. This is largely because AESA is more reliable and, increasingly, no more expensive than the older mechanical (a small dish that moves around inside a dome) radar. AESA is also easier and cheaper to maintain, which makes a more expensive AESA cheaper, over its lifetime, than a cheaper (to buy) mechanically scanned radar.
AESA type radars have been around a long time, popular mainly for their ability deal with lots of targets simultaneously, and produce a more accurate picture of what is out there. But AESA was also a lot more expensive, and less reliable, than older radar technologies. That has 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 JSTARS aircraft possible, as it enabled it to locate vehicles moving on the ground. A new, smaller MP-RTIP AESA radar for the RQ-4 UAV can also spot smaller objects on the ground. As a result, with the RQ-4 UAV equipped with AESA, the U.S. Air Force has a choice between extending the life of the E-8 aircraft, or replacing them with the UAVs.
While AESA makes fighters much more effective, it's the many other uses of AESA that make this technology so attractive to warplane designers. For example, the U.S. Air Force has been equipping some of its fighters with electronic ray type weapons. Not quite the death ray of science fiction fame, but an electronic ray type weapon none the less. In this case, the weapon uses the high-powered microwave (HPM) effects found in AESA radar technology. AESA is able to focus a concentrated beam of radio energy that could scramble electronic components of a distant target. Sort of like the EMP (Electromagnetic Pulse) put out by nuclear weapons. The air force wont, for obvious reasons, discuss the exact kill range of the of the various models of AESA radars on American warplanes (the F-35 and F-22 have them). However, it is known that range in this case is an elastic thing. Depending on how well the target electronics are hardened against EMP, more electrical power will be required to do damage. Moreover, the electrical power of the various AESA radars in service varies as well. The air force has said that the larger AESA radars it is developing would be able to zap cruise missile guidance systems up to 180 kilometers away.