The US Navy has demonstrated a Northrop Grumman RQ-4 Global Hawk unmanned air vehicle as an airborne early-warning platform by using the existing Raytheon integrated surveillance suite synthetic-aperture radar (SAR) in an air-to-air mode.
The demonstration was carried out in February and March as part of a three-flight series under the Congressionally mandated Global Hawk Maritime Demonstration.
The Raytheon SAR was a standard production version, but with software modifications to its ground moving-target indication extraction system to allow for detection and tracking of aircraft.
No modifications were made to the physical integration of the radar, which is side-mounted beneath the aircraft nose and gimballed to allow lateral movement of ±45° to undertake ground surveillance.
Ed Walby, Northrop Grumman Integrated Systems business development director for high-altitude, long-endurance systems, says that the effective radar horizon for the system in air surveillance mode was around 160km (100 miles) from an altitude of 60,000ft (18,300m). Air picture data generated by the radar was passed in near real-time to the Navy, US Coast Guard and other agencies.
Development of a dedicated AEW version of Global Hawk is feasible, says Walby, but would require integration of a different radar type. The air-to-air mode will be standard on future production RQ-4Bs.