David A. Fulghum
Washington
Aviation Week & Space Technology
05/30/2005, page 24

MP-RTIP radar, built for the E-10 aircraft, has been secretly designed to jam cruise missile electronics

SEE IT, JAM IT, KILL IT

The technological walls separating radar, electronic warfare and missile defense are coming down.

This fundamental shift has resulted in development, not yet publicly acknowledged, of multifunction, active electronically scanned array (AESA) radars that can locate stealthy airborne targets and then jam their computers and guidance systems with at least enough effect to drive them off course by using a focused beam of X-band radar energy.

This weapons capability--against cruise and air-to-air missiles--is one of the closely held effects that are to be produced by the Northrop Grumman/Raytheon Multi-Platform Radar Technology Insertion Program (MP-RTIP) now under development for use on the E-10 airborne surveillance aircraft.

The technology roughly parallels the emerging development of ground-based high-power microwave (HPM) devices as anti-missile systems. In fact, the first such HPM weapon, under development by Raytheon, looks much like a large AESA radar. Analysts contend that it should produce broadband pulses of microwave energy that can jam electrical components at ranges of perhaps 100 mi. and destroy electrical components at tens of miles.

What's not mentioned, but would seem likely, is that similar effects would be inflicted on manned aircraft, helicopters and unmanned reconnaissance/ combat aircraft. (This story was put together from a series of interviews with military and aerospace industry specialists over several months.)

BOTH THE GROUND-BASED HPM weapon and the MP-RTIP radar operate in the X-band frequency because small X-band transmitter/receiver modules are now relatively cheap. They are being built in large quantities for a variety of radars, including those on all the new-generation U.S. strike aircraft.

HPM weapons tend to use a broader band frequency pulse, usually in the 2-12-GHz. range. MP-RTIP is more precisely focused in the 8-10-GHz. band. Both have a weapons effect. A large, ground-based HPM device will have a greater destructive effect at long range because of large antenna size and greater power output. The airborne AESA will have the ability to jam (but not damage) electronic devices at long ranges because its beam is more narrowly focused for its primary job of precision targeting.

Aiming for a ground-based HPM weapon requires much less precision than a laser weapon and is therefore cheaper. The weapon's beam is several times larger than the size of the missile it's targeting. The effect from a large-aperture system with virtually limitless power resources from the local electrical grid would be enough to "blow the electronics out of an enemy missile," says a longtime Pentagon radar specialist.

THESE EMERGING capabilities lend weight to the opinion of some aerospace industry planners that high-power microwave and radio-frequency devices will quickly pass lasers as the directed-energy weapons to first see operational use in combat for the key missions of missile defense, airliner protection and urban combat.

The E-10, when completed, is to be capable of engaging airborne targets as a function of its Airborne Moving Target Indicator (AMTI) mode. The U.S. Air Force has acknowledged that the E-10 is to be a crucial node in cruise missile defense. But, attention has been focused only on the radar's projected capability to locate and target small and stealthy objects like cruise missiles.

There have been clues to the AESA's weapons-like capability, however. A handful of F-15Cs flying from Elmendorf AFB, Alaska, had been modified with the APG-63(V)2 AESA. The new radar, made of up of hundreds, perhaps thousands, of transmitter/receiver modules, can scan for targets, keep a continuous track of dozens of them, guide missiles and communicate. Perhaps most interestingly, all the power of the radar's TR modules can be focused to jam enemy radars in a narrow frequency band. The AESA-like capability also is being installed on the Navy's F/A-18E/F Super Hornets and USAF's F/A-22 Raptors and F-35 Joint Strike Fighters (AW&ST Oct. 18, 2004, p. 58; Oct. 4, p. 49).

"You don't need to burn out the electronics to make a missile go off course," says the Pentagon radar specialist. A large pulse of energy can affect the sensor's infrared focal plane array or the processors that help guide the missile and identify its targets.

But, a large radar frequency emitter with enough power can destroy electronic components.

"If you had a billboard-size aperture and the necessary electricity [from a city's electrical grid] for 25-35 dB. of gain, you could concentrate the power from an X-band [HPM device] into 1 degree and jam missiles at ranges out to perhaps 100 mi.," he says. "If the missile's electronics package had no protection, you could get in there and destroy the circuitry of a missile." Other radar researchers and missile-threat specialists say such a system would have to damage or disrupt missile systems at "at least tens of miles" to be useful against shoulder-fired anti-aircraft weapons.

The scenarios offered by other radar and missile specialists suggest that those designing the MP-RTIP radar and ground-based HPM weapons know details of the electronic circuitry of the missiles they are targeting. The beams they produce are capable of entering vulnerable parts such as antennas, radomes, fiberglass panels and nonconducting sections. Energy from the high-power signal would be coupled into the missile's electronic systems to overwhelm the normal, low-power signals.

The E-10, with its 4 X 21-ft. radar aperture, has been designed to jam cruise missile guidance at a tactically useful distance. While at least one radar specialist concedes that the radar's power probably could be focused enough to damage electronic components of enemy missiles, such action would be a "serious misuse of an excellent radar's capabilities," he says.

Directed-energy weapons specialists are cautious when predicting the appearance of offensive HPM weapons on tactical size aircraft or UAVs. To use the power shaft available on the Joint Strike Fighter--for example, to energize a directed-energy weapon--is still about 15 years away. However, senior Pentagon officials have suggested that some smaller or one-shot air-launched HPM weapons could begin appearing in 2-4 years if there's adequate funding (AW&ST July 26, 2004, p. 34).