THE GREAT RADAR RACE: AESA DEVELOPMENT IN HIGH GEAR

There is an arms race in full swing right now but you can’t see, hear or feel it’s products. Active Electronically Scanned Array Radar technology is nothing new, forms of AESA technology have been around for years on larger scale radar products such as early warning ground radars and missile ships, most notably the US Aegis Naval Warfare system. What is relatively new is the ability to pack this technology into the nose of fighter aircraft and everyone wants them for a slew of good reasons.

Tactical AESA radars provide significant improvements in almost every area of the past mechanically scanned array radar’s envelope. First off they don’t have any mechanical moving parts, such as servo motors that in legacy designs had to swing the radar dish around at high-speed and under large amounts of gravitational force. The wear and tear maintenance on these systems was legendary, causing more aborted missions than almost any other aircraft component failure for radar equipped fighters around the world. The reliability enhancements via AESA technology have been claimed to equal between a 20X and 50X increase in reliability over older traditional models.

These new radars also see farther and can detect smaller targets at greater ranges than ever thought possible. When you discuss comparative radar technology you need to talk about standard sized targets at different ranges. In some cases manufacturers claim detection sensitivity increases by as much a 50%, which is an amazing boost in capability. A byproduct of this higher resolution detecting power is that small, low flying targets such as cruise missiles can now be seen at standoff distances and engaged with some efficiency, a fleeting capability in the past. The same can be said for low observable (stealthy) targets, as nothing it totally stealth, AESA technology means you can detect these targets at longer ranges, giving the pilot more time to react and to initiate the “kill chain” sequence of events that will take out the target. In in modern times, aerial combat can be won or lost based on who sees who first and AESA technology provides a definite surveillance edge.

For multirole aircraft such as the F-15E, F-16E/F and F/A-18E/F/G the AESA radar can act both as an electronic attack weapon and an electronic counter-counter measure. The power and agility of the AESA’s beams can be used as a weapon, jamming or even frying out enemy radars. In other words, it can listen to the frequency of the bad guys radar and send erroneous returns or even a deadly pulse back to that radar, blinding or even crippling it. This is a powerful capability and will offer some sort of electronic attack to every aircraft that is equipped with AESA technology. More so, Using electrons over $500,000 missiles is always a smart choice economically. Also the amazing power and resolution of these radars allow for better positive detection of enemy targets in an electronic warfare saturated environment. Basically they can “burn through” jamming techniques used by the enemy in order to get a positive lock much earlier than in the past.

The power and focusing ability of the AESA radar has made noncooperative target recognition much easier that the past. Although this is highly guarded technology it is reasonable to assume that an AESA radar can take a synthetic aperture radar “image” of its target to compare to a database of 3D vehicle models and thus classify the exact type being targeted along with displaying the % of certainty at the time of interrogation and classification. It can also use the less comprehensive method of counting the blades on the engine face of aircraft that has seem to have been the legacy method over the past couple decades with greater certainty. It may even be possible to tell the exact load out of the enemy aircraft in question via high-resolution radar imaging with a robust software database for the system to compare the radar image to. This is amazing and relevant technology as “Blue on Blue” friendly fire incidents have become politically unacceptable in the modern-day of coalition lead operations. Furthermore, knowing the exact identity, and thus capabilities of the threat you face at long ranges is a massive tactical advantage in aerial warfare.

On the other hand, AESA radars can be very hard to detect by the enemy via multiple methods such as frequency hoping, modulating a continuous wave signal and using the very least amount of power to detect, track and engage a target. Whereas in the past standard radars can easily give away the emitting aircraft’s presence and even general location, with AESA’s low probability of intercept technology this has become much harder. Further, AESAs can work in passive mode, and can “listen” on certain bands for radar returns using a remote emitting source such as another aircraft. In other words it is possible for a AESA array to be in passive mode while another aircraft is in active mode at a standoff range, allowing the passive user to silently target and engage targets, possibly only turning on their radar at the last moment prior to attack. As AESA technology develops the AESA radars ability to work as a passive array and the tactics that go along with it will be very exciting to see develop. In the past, passively scanned array radars have been proposed to be used to intercept stealth aircraft using only the electromagnetic noise in the environment such a cell phone and radio transmissions and other bandwidths that modern-day stealth aircraft were not built to fully evade. With a modern networked battlefield, and as receivers become more sensitive, passive scanning may become the antidote to enemy stealth technology

Another great byproduct of AESA technology is the ability to “interlace” different radar functions or modes so that a more accurate picture of the battle space can be fused together for the warfighter. On older mechanically scanned radar models the radar actually had to swing around and look at different areas of the sky or the ground. With AESA technology, because the radar beam is scanned electronically, much more of the sky and the ground can be scanned at any given time. This allows for not only a more updated radar picture and a more robust ”scan while track” capability than in the past, but it also allows ground mapping functions and aerial scanning functions to be executed at the same time. In aircraft such as the F-15E or F/A-18F this means the pilot in the front seat can  scan for aerial threats while the Weapon Systems Officer in the back seat works at navigation and/or finding their ground target or surveying enemy territory using the high resolution synthetic aperture radar modes while produce a picture quality like map of the ground. This has never been achieved before, decoupling the front and back cockpit truly allows for maximum situational awareness over the battlefield. In single seat fighter similar technology is used to give the pilot a much better picture of the air and the ground at the same time offer a truly amazing advance in capability.

Finally, AESA radars and their incredibly capable software and computer backends can act as information transmitters as well. This sounds strange but it is true, because the radars can modulate and transmit radiation so quickly they can also eventually transmit large amounts of information such a high-resolution streaming video to receivers. This is a shadowy part of emerging AESA technology, but it may be very relevant. Being able to send lots of data across the battlefield is a weapon in itself and somewhere where America is constantly trying to catch its breath. Using a AESA radar as a major network transmission device may prove to be an incredible eventuality. Further, the AESA radar may also be able to send “weaponized data” down to enemy receivers. For instance telling an enemy integrated air defense system to turn off or to point their radar dishes in another direction etc. Then bombarding them with radiation in an attempt to destroy the receiver if the first non-invasive attempts to “hack into” the nework do not succeed. In other words, the AESA can also be a smart ray gun of sorts, able to stun the enemy on many levels or even blind them permanently.

The only downside to aerial AESA radars is that unlike mechanically scanned arrays AESA arrays lose energy out of their “side lobes.” So detection ranges around the outside cone of the radar’s beam can decrease drastically. There are some innovative solutions to this problem in the works. The Eurofighter Typhoon’s soon to be realized “CAPTOR-E” AESA set uses a “swashplate” like design that scans the radar a bit to each side mechanically, thus giving a wider aperture or field of view for the system when compared to fixed mounts. This system has said to be able to give about 200 degree scanning field which is amazing. The F-22 was meant to have passive arrays on each side of the nose, a latent capability that was built into the aircraft but has not been funded to do lack of funds. This would give the F-22 a much wider field of view than currently realized via the hard mounted APG-77 radar set. It also must be noted that an AESA’s detection ability is somewhat dependent on the size of aperture itself, or the area of nose’s ”real estate” available for mounting. A larger array means more transmit receive modules and thus more power and range. It is for this reason that the F-15E’s new APG-82 radar set is more capable than the F/A-18E/F APF-79 although it uses almost the exact same “back-end” hardware. So legacy cold war aircraft like the F-15, SU-27 or MiG-31 with their massive nose cross sections can really capitalize on this new technology. On a side note imagine how big and powerful of an AESA we could have put in an F-14 as the AWG-9 was one of the most powerful and large air intercept radars ever fielded to begin with.

With all this in mind you don’t have to wonder much about why AESA radars are in such high demand. Their ability to breathe new life into old aircraft designs is very exciting, and when you add a common datalink system like Link16 to these airframes, the AESA radar’s picture can be spread to all the users in the battle space and visa versa, which is a massive force multiplier and allows for a high-resolution gods eye view of the air picture to be built even without an AWACs. Further, although their cost is substantial (roughly five to ten million dollars per unit) their performance benefits and enhanced reliability make them a no-brainer for any air arm that is trying to modernize in these harsh economic times.  It will be exciting to see where the great radar race takes us, but it is very possible that the age of the aerial ray gun has arrived…

A bit about the F-35′s APG-81 AESA radar set-

Russian design using a swashplate type mechanism

The F/A-18E/F/G’s APG-79