U.S. warplanes flying over Syria today find themselves operating within the range of Russian S-400 surface-to-air missiles . While the U.S. military is unlikely to intentionally attack Russian forces in Syria, the situation highlights the importance of suppressing enemy air defenses—one major tactic U.S. flyers have long relied upon is radar jamming, or saturating enemy radars with “noise” and false signals so that they can’t track and fire upon friendly airplanes. The U.S. Navy has relied on the ALQ-99 jamming system for nearly half a century, even as opposing radars grew in ability. However, by the beginning of the next decade it will begin fielding the superior Next Generation Jammer, boasting significant electronic-attack and signal-intelligence capabilities.
The powerful ALQ-99 tactical jamming pod first entered U.S. Navy service in 1971, carried by the EA-6 Prowler, an electronic-warfare variant of the A-6 Intruder carrier-based attack plane with a four-man crew. The U.S. Air Force eventually supplemented the Prowler with faster and larger EF-111 Ravens , informally known as Spark Varks because of the intense static buildup their jammers generated. Both planes proved effective in suppressing air defenses in Iraq and Libya. However, the Raven was withdrawn from service early in 1998, as the imminent retirement of the F-111 fleet made it prohibitively expensive to operate. Seventeen years later, the Navy retired its aging EA-6s in favor of new EA-18G Growlers—special electronic-warfare variants of the F-18 Super Hornet. The two-seat Growlers are much faster and better armed, but must rely on automation to make up for the reduction in crew size.
The Marine Corps will continue to fly its Prowlers until retirement in 2019, leaving the Growler as the sole remaining tactical jammer. Overall, demand for jamming aircraft has remained high even as the quantity has diminished. The jammers have even proven useful in the war against ISIS by scrambling ISIS communications and disabling roadside bombs .
Jamming, however, is not a panacea against enemy radars—it sharply degrades their effective range but does not neutralize them entirely, and jamming aircraft have to be careful not to get too close to the defenses they are scrambling. Furthermore, while the analog-based ALQ-99 has abundant power, new radars boast greater power as well, and are more capable of switching frequencies and networking with friendly sensors to overcome the effects of jamming.
Enter the Next Generation Jammer program, the first documents for which were released by the Pentagon in 2004, with the aim of bringing jamming into the digital age. The NGJ had originally been envisioned as an automated pod for use on single-seat F-35 Lightning stealth fighters, which would serve in all three branches of the military. However, this concept proved much more expensive and time-consuming than expected—which could summarize be the F-35 program in a nutshell. Instead, the Pentagon eventually decided to focus on re-equipping the Navy Growlers with the new jamming system, and in 2013 chose the design proposed by Raytheon over three major competitors.
The NGJ is designed to work against a full spectrum of radars, but different radars will require different countermeasures, which Raytheon is developing on a staggered schedule. The upcoming Increment 1 pods are designed to jam mid-band engagement radars commonly used by ground-based surface-to-air missiles, which pose the greatest threat to U.S. aircraft today. Once available, the EA-18 will carry two of the mid-band pods—one under each wing.
However, the Growler will retain a single fuselage-mounted ALQ-99 pod optimized for jamming low-band radars until the Increment 2 NGJ pod is ready further into the 2020s. Low-band or surveillance radars have a broader scanning area, and are effective at tracking enemy aircraft—even stealth fighters!—but are too imprecise for targeting weapons. Nonetheless, surveillance radars help the more narrowly focused engagement radars know where to look for enemies, and a forewarned engagement radar can ambush a stealth fighter at short range. Thus, as the number of stealth aircraft swells with the production of the F-35, jamming low-band radars will become more and more important.
Eventually, Raytheon also plans to develop an Increment 3 system for jamming high-band engagement radars, which are common on fighter planes.
The fifteen-foot NGJ pods employ an Active Electronically Scanned Array radar with gallium nitride components that amplify radio energy. Program manager Capt. John Bailey claimed in a seminar that the NGJ can generate ten times the radiated isotropic power level of the preceding ALQ-99, and that the signal is “cleaner,” minimizing the collateral interference with friendly signals. Just as importantly, the NGJ can jam multiple frequencies—Captain Bailey claims four times as many—and is designed to be an “agile” jammer, capable of analyzing new enemy signals and adjusting its own frequencies to counter them literally on the fly. Moreover, because the NGJ is a digital solid-state open-architecture system, it can be upgraded with new “threat libraries” of hostile hardware, allowing it to be easily—and cheaply—upgraded to match new adversary capabilities. Finally, the NGJ pods can do all of this without draining power from the Growler carrying it, thanks to its ram air turbine.