Saab unveils new fighter radar
Saab has successfully completed a first test flight with its new (and as yet unnamed) fighter X-band Active Electronically Scanned Array (AESA) radar. The new “Saab AESA fighter radar” represents a new evolution of Saab's existing PS-05/A radar family, marrying a new AESA antenna array to the existing ‘back end’ of the PS-05/A Mk 4 radar that is currently fitted to JAS 39C/D Gripen fighters.
Tomas Augustsson, writing in Svenska Dagbladet (in Swedish and behind a paywall) quoted Micael Johansson, CEO of Saab as saying that: "This is a milestone for us as a company. Making a radar for fighter aircraft is usually very expensive. We have financed the development ourselves and have managed to find a way to make it cheap.”
The new radar was flown for the first time on 8 April, fitted in a JAS39D test aircraft, serial 800 (originally built as the two-seat JAS39B Gripen prototype). The 90-minute sortie from Saab’s Linköping factory airfield was successful, the radar collecting data while detecting and tracking various targets of opportunity in the air and on the ground. Ground-testing of the new antenna array began well over a year ago.
Anders Carp, Senior Vice President and Head of Saab's Surveillance business area, said that the trial had been very successful in terms of both stability and capability, and expressed his satisfaction with the results. Flight trials are expected to continue for about three or four months, and to encompass around 15 test sorties. This will include tests against representative fighter targets.
Saab has continued to develop AESA radar technology, but up to now has not had a proven AESA-equipped fighter radar available and was thus unable to provide the primary sensor for its own new Gripen E/F. The Gripen E instead uses a Leonardo (Selex) ES-05 Raven AESA radar with Gallium Arsenide (GaAs) transmit/receive modules (TRMs) and an innovative swashplate repositioner.
What is currently known simply as the “Saab AESA fighter radar” comprises a new fixed GaN array married to the back end of the mechanically-scanned PS-05/A Mk 4 radar used by the Gripen C/D, and with a new signal processor. Saab has built most of the new radar, including the new TRMs. These are being manufactured in Gothenburg, a former Ericsson plant that is now Saab’s primary radar design and production facility. Saab say that the new radar is ITAR-free, and not subject to any restrictions imposed by the US Government under its International Traffic in Arms Regulations. The company claims that the new radar is now ready to go to market, and that integration on a customer’s Gripen C/Ds would take between 12 and 18 months including the completion of development and testing.
The new AESA radar leverages Saab’s growing experience with Gallium Nitride (GaN) technology gained through development of the Erieye ER S-band surveillance radar and the Giraffe series of ground-based radars as well as the Gripen’s EW system, and the new Arexis electronic warfare jammer pod.
GaN semiconductors are characterised by lower power consumption and improved heat resistance compared to Gallium Arsenide, and this allows longer ranges to be achieved, wider bandwidth and greater reliability, and availability, as well as improved ECCM (Electronic Counter-Countermeasures) capability. The new fighter radar is also expected to have better performance against small targets, and will be better able to support advanced weapons – exploiting the full range of the MBDA Meteor BVRAAM, for example.
Saab opted for a fixed antenna array, and reject suggestions that not having a repositioner makes the radar in any way old-fashioned. Carp suggested that advanced digital processing can overcome most of the problems associated with a fixed antenna, and instead cited the company’s desire to avoid the use of unnecessary moving parts. This is, to some extent, missing the point. Simply rotating an AESA array does not require the kind of complex motors required to point a conventional radar antenna, and provides increased range at higher off boresight angles, and confers a much-expanded field of regard without a significant weight or reliability penalty. Moreover, a repositioner allows antenna position to be optimised for reduced RCS. Carp did say that a repositioner could be incorporated if tests showed that it was necessary.
The most obvious application for the new radar will be as an upgrade and retrofit option for existing Gripen C/Ds, and indeed for any new-build first generation Gripens for new customers. Saab’s CEO, Micael Johansson has expressed his hope that the Swedish state will buy the new radar to upgrade the 95 Gripen C/D aircraft currently in Flygvapen service. These are planned to serve well into the 2030s, but no upgrade has been funded.The new radar would require no additional power or cooling compared to the existing M-scan radar. The new radar could of course be fitted to other fighter types, particularly as an upgrade option, and Carp observed that there were many 4th Generation Fighters that “need to be upgraded.”
Coupled with his CEO's remarks about having found ways to develop the radar cheaply, Aerospace Analysis & Insight wonders whether Saab have managed to come up with a Grifo or EL/M-2032 for the 21st century - a powerful, highly capable radar that is affordable enough for retrofit and for lighter, cheaper combat aircraft platforms?
Carp says that there are no plans to equip the new-generation Gripen E/F with the new radar though he said that it could be substituted for the Raven if a customer specified it.
The new radar is designed for fighter aircraft but is modular, adaptable and scalable and can be adapted to a variety of platforms and applications, perhaps including installation in advanced trainer aircraft like the Boeing/Saab T-7A Redhawk and the proposed Gripen Aggressor aircraft. The radar could also be scaled-up to “almost Erieye ER size” as an X-band surveillance sensor. Ship- and UAV-based applications are also being studied.
The new Saab AESA fighter radar is the latest in a long line of Saab/Ericsson radars designed for fast jet applications, and represents the latest in a series of efforts to provide an improved and more modern radar for Gripen. These efforts date back many years.
The PS-05/A Mk 3 was an improved mechanically-scanned radar developed under the JURA (JAS Upgraded Radar) programme, with a new signal/data processor. The PS-05/A Mk 4 was another M-scan set, and was developed under the GRETA (Gripen Reconnaissance and Enhanced Target Acquisition) project. It introduced a high-resolution synthetic aperture radar (SAR) capability and enhanced ground moving target indication/tracking. Saab formally unveiled the PS-05/A Mk4, in April 2015.
The first AESA version of the PS-05/A was the Mk 5. This was described as using the Mk 4 ‘back end’ with a new active electronically scanned array (AESA) antenna and new radar software. Upgrades were at one time expected by 2012, and the radar was said to be available for export around 2010. I’m still trying to work out whether it came before NORA or after?
There was an AESA radar named ELIT, but I haven’t been able to dig out anything about it so far.
The Saab Ericsson NORA (Not Only a RAdar) programme saw Ericsson integrating a Raytheon AESA antenna (reportedly delivered in 2004) with the PS-05/A. A radar was fitted to a Saab Viggen test aircraft (but I don’t know whether it was flown, nor, if it was, when that was). It was once expected to be introduced to the Gripen as part of a planned mid-life upgrade (MLU) from about 2010. The NORA program was halted due to restrictions on US technology exports.
In May 2008, Saab revealed that the Gripen Demo development platform would be equipped with a new radar that Saab was developing in collaboration with Thales. (I’m not sure whether that ever happened). This new radar combined the active array from the Thales RBE2-AA (as used on the Rafale) with the existing signal data processor and exciter/receiver of the PS-05/A radar.
In March 2009 Saab announced that it had entered into a co-operative agreement with SELEX Galileo to jointly develop the ES-05 Raven AESA radar for the Gripen NG programme. But the Raven radar on the Gripen E “sits there because Saab's new radar was not ready when the decision on the new Gripen E was made,” according to Saab CEO Micael Johansson.
Saab has to tread a careful path with its new radar. The company cannot undermine its Gripen E product, nor the radar it is fitted with, in the face of ongoing export campaigns in Finland and Canada. Yet at the same time, to concede that the new radar may not mark an improvement over the Raven could significantly damage its sales prospects, while both the Raven and Saab’s new radar have now been mooted as possible candidates for a first generation Gripen upgrade. Awkward!
Johansson does claim that Saab has “taken a generational step with our new radar,” and has cautiously expressed his “hopes that the radar will also be updated if Sweden eventually decides on a new version of Gripen E - something that may come in 15 years.”
Saab continued to pursue the development of its own AESA fighter radar, and unveiled a design (again based on the back end of the PS-05/A) at the 2015 ADEX show in Seoul. This was offered to Korea for the indigenous KF-X fighter, and was intended to be co-developed in collaboration with South Korean industry. This is an entirely separate project to the recently revealed Saab AESA fighter radar.
Saab has also offered an AESA radar based on GaN technology for India's Tejas LCA fighter aircraft, closely integrated with a GaN-based compact electronic warfare suite. This project (which emerged in 2017) is also distinct from the newly unveiled Saab AESA fighter radar.
Carp did acknowledge that the new radar’s form factor was “more or less the same” as a radar being supplied to a “US customer” who he declined to identify. This is understood to be the US Office of Naval Research and the Office of the Secretary of Defense Foreign Comparative Testing Program. US Naval Air Systems Command announced the award of an uncompleted $8.2 million sole-source contract to Saab Defense and Security USA LLC in October 2018 for research and for the development of an X-Band Active Aperture Array radar prototype, and for the provision of related auxiliary equipment and engineering services. The prototype radar was to be a high-power, lightweight solid-state phased array X-Band radar incorporating GaN power amplifier technology. Work was to be performed in Gothenburg, Sweden (80%); and East Syracuse, New York (20%), and was expected to be completed in June 2020.
The new radar for the US, which may be designated as the Future X-Band Radar (FXR), was intended to be used for evaluating the characteristics of GaN technology within the SWaP (Size, Weight and Power) constraints of fighter-class radars. It was required to operate in sea, air, and land environments, requiring airworthiness certification and sufficient resilience to allow developmental testing in those environments.
This radar was required to use “well documented and non-proprietary interfaces and controls”, and all aspects of the hardware and raw data products from the system had to be unclassified to facilitate testing and storage in uncontrolled spaces. The radar was required to have independent transmit and receive channels for each subarray to enable the transmission of different signals across the array, with architecture allowing RF inputs and outputs to the transmit-receive modules to be accessible through minimal hardware redesign in order to enable azimuthal digital beamforming simultaneously across a 90° field of view. For additional system agility and operational modes, the radar system had the means to arbitrarily set analogue amplitude and phase weights per element and per pulse.
