Aviation Week & Space Technology
May 27, 2002

Air Force Embraces Jammer, But Plots Independent Course

By Robert Wall and David A. Fulghum, Washington

With only days to go before a high-level review of electronic warfare, the U.S. Air Force is signaling that it may be ready to narrow its differences with the rest of the Pentagon and embrace the need for a new standoff jamming aircraft.

USAF planners had long argued that the service's EW requirements are changing and that the introduction of more stealth aircraft and active electronically scanned radars--which can be used to jam narrow frequencies--may eliminate the need for a jamming aircraft. But now service leaders acknowledge they are not there, yet.

"In the intervening period, we still think we are going to need some sort of standoff jammer," said USAF Secretary James G. Roche. The shape of the interim system has not yet been determined, although putting jamming equipment on B-52s is one option.

THE SERVICE HAS 17 "excess" B-52s that Congress won't allow to be retired. They could be used for the electronic warfare mission. Moreover, the aircraft have wing stations to carry jamming pods and enough endurance to provide long-term support. The B-52 also could be linked with Rivet Joint aircraft and other intelligence systems to improve its jamming performance.

The Air Force's revived interest in EW comes at a key moment. Pentagon acquisition chief E.C. (Pete) Aldridge, Jr., has told the service and the Navy to report on their electronic warfare plans in early June, with particular emphasis on how to replace the aging EA-6B Prowler. Aldridge has indicated he is irritated by the Air Force's lack of action. "They need to make a decision rather than continue to study something," he said.

The Navy, for its part, has pretty much determined it wants to replace EA-6Bs with the EA-18, an electronic warfare version of the F/A-18E/F. The service wants to leverage the ICAP-3 jamming system currently being developed for the EA-6B as the baseline mission equipment. How many EA-18s the Navy buys will depend largely on whether it will be expected to provide jamming support for the Marine Corps and Air Force, or just serve its own needs. The total could be as high as 180 aircraft, although for Navy-only needs, this could drop to around 100 aircraft.

But the Navy's vision of buying an escort jammer that would fly with the strike package doesn't match the Air Force's concept of operations. "We believe our needs are different because we expect, in time, to have very stealthy airplanes," Roche said. "What we are most concerned about is an unanticipated pop-up [threat] to the side or behind [the stealth aircraft]," which can be dealt with using a long-dwell, standoff jammer. The jamming also wouldn't have to be as high-power and can be more focused, since stealth aircraft are already hard to detect, Roche indicated. Moreover, an escort jamming aircraft isn't suitable to supporting stealth aircraft, he noted, since the electronic noise it emits would alert enemy air defense operators to an in-bound flight of stealth aircraft.

IN ADDITION, Roche said, "the money savings are not going to be in the platform." Instead, he argued that savings would be generated by sharing the development bill for the jamming suite. And since the Navy and Air Force are concerned largely with the same frequencies and techniques, the electronic equipment can be common, he maintained.

But the Air Force still has to convince others about the wisdom of its strategy. So far, Aldridge's own vision appears to be different. "We can't afford two different airplanes for the two services. There's going to be an integrated EA-6B replacement of some type," he said.

A key element of the new Air Force activity is a research and development project for a lightweight modular support jammer (LMSJ). The concept is to design and develop a scalable jammer package that could be installed in different sizes on everything from an unmanned expendable aircraft, to a fighter--with underwing or internal carriage--to a wide-body aircraft. USAF engineers envision a "Lego-like" architecture where it could combine different blocks or modules to make the jammer more capable.

The Air Force wants to achieve a rather broad frequency coverage from 20 MHz. to 4 GHz. to be able to disrupt search and acquisition radars and command-and-control networks that are part of an integrated air defense system. Only fire-control radars are not slated to be covered by the system, since there aren't enough of them to warrant the spending, the Air Force said.

LMSJ is expected to yield new techniques to more cleverly fool enemy air defense operators. Among them would be deception jamming modes to insert multiple false targets that can be individually manipulated into enemy air defense systems. Noise-based screening approaches also will be considered. "Newer techniques rely less on brute-force noise jamming approaches and the very high jamming powers needed to make them effective," the Air Force said. Lower power systems also would be less expensive and smaller, thereby opening the door to an entirely new class of jamming systems.

Air Force engineers believe they can take advantage of several technologies, such as efficient wideband solid-state RF power amplification devices, advanced antenna array apertures and low-cost jamming electronics, that have matured in recent years. Among the challenging areas, the Air Force counts high-power, high-efficiency solid-state transmit amplifiers; broadband low-frequency transmit apertures covering HF, VHF and UHF; and the modular transmitters and apertures.

The Air Force hopes to develop a flyable brassboard, although the initial four-year, $5-million effort does not include flight testing. The focus of the project is on the "back end," which encompasses the jammer exciter, transmitter and transmit aperture, rather than the receive aperture and receiver/processor. To enable a full-up demonstration, the LMSJ would be combined with a front end developed for the Air Force Research Laboratory's Advanced Threat Alter and Response brassboard system.

ANOTHER EW-RELATED research thrust involves increasing the frequency coverage of active electronically scanned radars. Currently, those systems are very narrow-band and may not operate in the frequencies that really need to be jammed, according to industry officials. But Roche said ongoing work stresses increased frequency coverage to make the radars more effective in the jamming mode.

In the near term, the Air Force also plans to upgrade the EC-130H Compass Call communications jamming aircraft. Modification of the first of the Block 20 aircraft into the Block 35 configuration should begin this summer. Eventually, all 13 aircraft will be upgraded to that standard. It will provide a common hardware infrastructure that should allow future upgrades to be largely in software, said Lt. Col. Robert Jackson of the Compass Call System Program Office at Wright Patterson AFB, Ohio.

THE SERVICE ALSO PLANS to enhance Compass Call's Spear pod, the latest feature to be added to the aircraft. The pod made its debut on the two EC-130Hs deployed to support operations in Afghanistan. Last year, Spear (special emitter array) was near the end of its development when it was fielded early to support the conflict. The system essentially allows Compass Call to broadcast jamming noise in four independently steerable beams using 144 discrete transmit elements. The system is designed to thwart modern communication systems and emitters using emerging technology, said Michael Powell, a development engineer for BAE Systems. The Air Force now is working on expanding the system's frequency coverage.

A Compass Call carries two interchangeable pods under each wing. So far, the Air Force has enough pods for three aircraft, but eventually plans to equip the fleet.

The two aircraft that supported Afghan operations--both in the Block 30 configuration--conducted 108 missions, deploying 48 hr. after being put on alert Sept. 22, and recently returned from their deployment. Despite the poor infrastructure in Afghanistan, there was substantial communications traffic to jam, including cellular telephones, aircrews said.

To support the conflict, some of the linguists (four fly on each mission) underwent intense language training prior to deploying, said Lt. Col. William Reaves of the 41st Electronic Combat Sqdn. There was already a cadre of Arabic speakers, which proved useful in monitoring many Al Qaeda forces. But expertise in Pashtun, one of Afghanistan's indigenous languages, had to be generated quickly.

Operations in Afghanistan differed from other conflicts in that aircraft largely had to support ground forces rather than focus on protecting aircraft. Moreover, because of the high mountains, the EC-130Hs had to establish orbits closer than normal to enemy forces, which resulted in exposure to antiaircraft fire on several occasions, said Capt. Chris Kirschman, who supports Compass Call at Air Combat Command.

The new operational mode has increased aircrew interest in self-protection equipment. Currently, the EC-130H is defenseless. Program managers hope to obtain Air Force funding for missile warning equipment and chaff and flare dispensers. While crews would like more sophisticated countermeasures, they may be too expensive.

"Self-protection is definitely a requirement that has been identified," Kirschman said. To reduce their vulnerability, the aircraft flew primarily at night, and crews tried to assess an operational area to gauge the presence of infrared-guided surface-to-air missiles.

Another upgrade looming for Compass Call is Link-16, which should give the aircraft better connectivity with other USAF aircraft. That link should allow RC-135 Rivet Joint signals intelligence aircraft to communicate directly with Compass Call. The Rivet Joint could monitor enemy radars and tell Compass Call crews whether their jamming is successful.