NGJ to rectify past neglect of electronic and information warfare capabilities
Technologies being offered up by the aerospace industry for the Next Generation Jammer (NGJ) are still closely held, but clues are emerging.
The active, electronically scanned array (AESA), for example, is now a part of all the competing teams' offerings, and that offers the potential for NGJ to become both an electronic sensor and a weapon. But there will have to be intense development to make it an operational reality, and funding for such esoteric capabilities can be elusive. Earlier options to upgrade theRaptor and Joint Strike Fighter with electronic information-gathering and electronic attack systems were not funded.
“That was the first thing that went, as a way to save money,” says Lt. Gen. (ret.) Dave Deptula, the U.S. Air Force's first chief of intelligence, reconnaissance and surveillance. “It wasn't the right decision. They are almost the only systems that can go into contested airspace and collect information. We are not limited by technology, but rather by bureaucratic, institutional and organizational inertia.”
Now much of that task has fallen to the NGJ program and the platforms that will carry the new electronic surveillance and attack system. To exploit electronic warfare, the military will have to operate across a very broad swath of the electromagnetic spectrum.
“We are looking at breaking a basic AESA array into four quadrants so that we can use each for a different function or point them at different targets,” says Mark Kula,vice president for tactical airborne systems. “Or you can use the total array to provide a very high-power capability. Tile arrays for NGJ are expected to produce nearly three times the power in a much smaller package,” he says. “If you use the quadrants of the array for different functions, power levels decrease. We're looking at the arrays in terms of elements that are steerable, directable and assignable in frequency.”
The advanced technologies include techniques to make segmented arrays work while minimizing co- or cross-channel interference. One solution involves developing receivers/exciters with lower harmonics. In addition, there is already work ongoing to use an aircraft's skin as antennas.
Raytheon is now building AESA panel arrays that are one-half to one-third the depth of traditional tile arrays. Elements that were stacked vertically are now arranged horizontally, which offers flexibility for installation.
Navy officials indicate that with the Unmanned Carrier-Launched Airborne Surveillance and Strike (Uclass) platform, for example, they would not want to carry a pod that would degrade the stealth signature. As a result, panel arrays are essential so that sensor elements can be integrated on or into the skin.
The use of gallium nitride transmitters is a key to wide-band capability and higher power levels. These devices generate heat; this requires cold-wall technology in which the tiles are embedded in an aluminum core that has coolant pumped through it at temperatures that permit longer duty cycles without burning up the electronics.
Stealthy vehicles will likely have antennas or arrays embedded in the skin that are then fed by transmitters somewhere in the interior of the airframe. But NGJ also comes with a requirement for more prime power than has been generated previously from a pod of its size. In fact, the power needed is several times greater.
“The Raytheon NGJ uses an internally mounted, ducted, ram-air-turbine generator that actually exceeds the power requirement,” says Nick Uros, Raytheon vice president for NGJ. “During recent testing, the power generator was housed in a full-scale model of our NGJ pod to demonstrate full power, transient load switching and effective thermal control at various altitudes and speeds. We demonstrated that we can generate more power than NGJ needs within drag-performance limits.”
In combat operations, Navy officials say the NGJ's electronic attacks will be supplemented by disposable, air-launched, EA weapons. The miniature air-launched decoy's jammer variant (Mald-J), for example, is a small cruise-missile type weapon being designed to carry a high-power microwave payload that can damage, blind or deceive enemy sensors from short range.
The advantage of Mald is that it is disposable and operates close to the target so that it does not have to put out so much power to effectively attack an electronic target.
Moreover, Mald is designed for a limited operational life, so there's little concern about heat buildup during the attack process. Its small size also has the advantage of making it difficult for enemy fires to shoot it down. Using Mald in conjunction with NGJ is a example of how multiple techniques can provide specific effects against integrated air defense systems.