24 April 2020
Saab’s new AESA array, seen here installed in JAS 39D “800”, has just under 1,000 gallium nitride transmit/receive modules. (Photo: Saab)
Saab has flown its active electronically scanned array (AESA) X-band radar in a Gripen fighter for the first time, the company announced on April 24. The flight took place at Saab’s Linköping airfield on April 8. During the 90-minute sortie undertaken by a JAS 39D trials aircraft (serial 800), the radar was successfully tested against aerial targets of opportunity and a range of ground targets. Speaking to AIN, Anders Carp, senior vice president and head of Saab’s Surveillance business area, noted that the radar demonstrated good capability and stability throughout the test mission.
“This is an important step in the development of our new fighter AESA radar,” said Carp in a company statement. “We see great possibilities for the radar, and its modular, adaptable and scalable design means it can also be used for a range of other applications.”
Under current plans, Saab expects to continue initial radar trials for around three to four months, with Gripen 800 due to fly around 15 times with the new sensor. As part of the evaluation, the radar will be employed against fighter targets.
Saab has been at the forefront of AESA radar design employing gallium nitride (GaN) technology, having pioneered the technology with its latest iterations of the Giraffe ground- and sea-based radars, electronic warfare equipment, and with the Erieye ER S-band radar employed in the GlobalEye surveillance aircraft.
The new AESA array is made up of hundreds of transmit/receive modules (TRMs), each one essentially a mini-electronically scanned radar. Radars made with GaN semiconductors have better performance—notably in terms of electronic counter-countermeasures, small target detection and wider bandwidth—than most current AESA sensors that employ gallium arsenide (GaAs) TRMs, while consuming less power and generating less heat.
What is currently known simply as the “Saab AESA fighter radar” comprises the GaN array married to the back end of the PS-05/A Mk 4 mechanically-scanned radar that is the current option for the Gripen C/D. Saab has built virtually all of the elements of the radar itself, including the TRMs that are manufactured in a foundry at the company’s primary radar design and production facility, the former Ericsson plant in Gothenburg. The company began ground-testing of the array well over a year ago.
In the Gripen installation, the array is fixed with Saab opting for this configuration due to its simplicity and reliability. The concept of using a repositioner was initially discarded as advanced digital processing can overcome most of the problems associated with radar performance at the outer edges of the scanning volume without adding the internal space required to accommodate a repositioning system. However, Carp commented that a repositioning system could be employed if trials showed that it was necessary.
The array is essentially the same as that which was ordered in late September 2018 for what Saab describes as an “undisclosed U.S. government customer”. At the same time, however, the Pentagon announced the award of an $8.2 million contract to Saab USA for the research and development of an “active aperture array”. The contracting agency was Naval Air Systems Command, with the array being intended for the Office of Naval Research and Office of the Secretary of Defense Foreign Comparative Testing Program. Saab has already flight-tested this array on another testbed in support of the U.S. program and delivered it to the customer earlier this year.
Saab claims that its new ITAR-free array is ready to go to market, and would take between 12 and 18 months to deliver given the need to complete development and testing, and to establish production. The radar has an obvious application as a retrofit for Gripen C/Ds, and could also be included as an option instead of the PS-05/A Mk 4 for new C/D sales, with the potential of revitalizing that aircraft’s sales prospects. Other opportunities include other fighter types, particularly as an upgrade option.
The company sees opportunities for the X-band radar beyond fighters, including installation in advanced trainer and aggressor aircraft. Moreover, the radar has been designed in a modular fashion, and is scalable. This opens up a wide range of applications, including scaled-up radars of almost Erieye ER size for X-band surveillance. Ship- and UAV-based opportunities are also being studied.
For now there are no plans to equip the new-generation Gripen E/F with the GaN radar as the GaAs-based Leonardo ES-05 Raven is fully integrated for that requirement, but it could be substituted if a customer specified it. Saab also points out that the work being performed by the company on an AESA radar for the KF-X fighter in collaboration with South Korean industry is a separate project.