Europe’s two next-generation fighter programs are gathering speed. What might their radar, EW, and communications architectures look like?

Europe is currently home to three combat aircraft programs – Dassault’s Rafale, Sweden’s Saab JAS-39E/F Gripen, and the pan-European Eurofighter EF-2000 Typhoon. 

But over the next two decades, this will reduce to two – the Future Combat Air System (FCAS), and the Tempest. Each is being developed by a specific bloc of nations – France, Germany, and Spain are developing FCAS, while Italy, Sweden, and the UK are working on the Tempest. 

Both of these sixth-generation systems should enter production and service in the early 2030s, according to official reports. Dassault and Airbus are developing the inhabited FCAS aircraft and accompanying Uncrewed Aerial Systems (UAS), while other FCAS contractors include Indra, Safran, MTU, Thales, and MBDA. 

Tempest takes a slightly different approach. Official announcements have stated that the aircraft will be “optionally piloted”, ie can fly as a conventional crewed aircraft or as a UAS, and BAE Systems, Leonardo, and Rolls-Royce are Tempest’s leading contractors.

Both FCAS and Tempest will include highly advanced radar and electronic warfare (EW) systems, along with mind-bending levels of networking. World War 2 underscored the primacy of airpower for operational and strategic success with Field Marshal Bernard ‘Monty’ Montgomery famously warning that, “if we lose the war in the air, we lose the war, and we lose it quickly.” 

Today the electromagnetic spectrum has a similar importance. The spectrum is the realm where situational awareness is enhanced via radar and Electronic Support Measures (ESMs) which gather intelligence, surveillance, and reconnaissance (ISR) data. The spectrum also supports communications links which let this situational awareness be shared with friendly forces at light speed. Radio’s use of the spectrum not only helps share situational awareness, but is also a vital command and control conduit. 

THREATS
American and allied mastery of the spectrum helped the US and its allies prevail during wars in the Balkans, Iraq, and Libya, and spectrum dominance will continue to become ever-more important. But near-peer strategic rivals to the US and allied nations are similarly keen to harness and dominate the spectrum. 

The US Department of Defense’s annual report on Chinese military developments pulls no punches, saying EW – and in particular, electronic attack – is one arrow in the People’s Liberation Army’s information warfare posture. The report says the “PLA considers EW an integral component of modern warfare and seeks to achieve information dominance in a conflict through the coordinated use of cyber and electronic warfare”. 

It adds that, “potential EW targets include adversary systems operating in radio, radar, (and) microwave…ranges, as well as adversary computer and information systems”. The report predicts that EW would be used by the PLA from the outset during any evolving crisis or full-blown war.

Combat aircraft venturing into such an electromagnetically-argumentative environment will face a two-pronged challenge. Radio frequency (RF)-dependent aircraft subsystems like radars, communications, and navigation will need protection from electronic attack. At the same time, the aircraft’s EW systems would need to be capable of attacking adversary radar and communications. 

Taking China as an example, the DOD’s report says the PLA has extensive early warning radar coverage along its coastlines. These are mirrored on islands occupied by China in the South China Sea (see article on Page XX) and inland across the country. Aircraft ingressing to and egressing from targets in China would face long sorties over densely defended airspace. 

Systems like the PRC’s China Electronics Technology Group’s SLC-7 L-band (1.215GHz to 1.4GHz) ground-based air surveillance radars are reportedly capable of tracking aircraft with low radar cross-sections, although may not provide sufficient track detail to provide fire control for a surface-to-air missile interception. But they could be used to direct intercepting fighters to an area where low observable aircraft are operating. 

While the PLA’s spectrum aspirations may initially seem far-removed from European future combat aircraft development, they are not. Any future confrontation between the PRC and a US-led alliance could see European actors flying the Tempest and/or FCAS in a coalition scenario, while both aircraft may find customers among allied nations in the Indo-Pacific. 

Military thinking in Russia – much like the PRC – has correctly understood that mastery of the spectrum is essential for military success. While Russia remains Europe’s predominant strategic rival, her armed forces are on a similar trajectory of electromagnetic enhancement to the PRC. 

In September 2021, Russian armed forces expert Roger McDermott published an article entitled Russia’s Military Boosts Electromagnetic Spectrum Capability. He warned that a decade of military modernisation has seen “the Russian armed forces…significantly (advance) their capabilities…specifically in electronic warfare”. 

The Russian Air Force’s ground-based air surveillance radar fleet is being enhanced with new systems. These include the NNIIRT 55Zh6M Nebo-M (NATO reporting name Tall Rack), a VHF (133MHz to 144MHz – 216MHz to 225MHz) radar which may have a range of 700km. Like the SLC-7, the 55Zh6M is thought capable of detecting aircraft with low radar cross-sections. 

Other radars with similar capabilities reported to entered service with the Russian Air Force include the NNIIRT 52E6MU Struna-1 and NPK NIIDAR 29B6 Container, the latter HF (3MHz to 30MHz) radar reportedly having a range of 3,000km. These radars are deployed to cover Russia’s western and southern air approaches, while its northern and arctic approaches are guarded by Rezonans-NE VHF radars with a reported range of 1,100km. The Rezonans-NE is joined by the NPK NIIDAR Podsolnukh-E HF coastal and ground-based air surveillance radars which may have a range of 450km.

POSSIBLE SOLUTIONS
The above capabilities show the Tempest and FCAS will both be fighting in potentially heavily congested electromagnetic environments, where their EW systems will play a leading role. 

EW has been at the heart of aircraft self-protection since the advent of radar in WW2, and the systems equipping these two aircraft will take this further. Neither aircraft will fight in a vacuum, and they will be heavily networked with offboard sensors and platforms. This will be achieved through traditional line-of-sight communications with standard voice traffic and tactical datalinks, reinforced with HF and satellite communications (SATCOM) providing over-the-horizon links. 

The aircraft will also have unprecedented access via secure internet protocol links to combat clouds, and will harness cloud computing to support tactical and operational electromagnetic manoeuvre. 

The potentials of such technology are almost limitless, and would require a whole dedicated article for a proper examination. Nonetheless, EW provides an instructive example. 

Let us suppose that a Tempest’s EW system has suddenly alerted the pilot of the aircraft’s illumination by a Rezonans-NE radar. Previously, an aircraft’s ESM would have to be programmed with the radar threats likely to be encountered during the sortie, thus ensuring the correct jamming waveform could be employed should they be encountered. 

But the limitation of this is that it might be difficult, if not impossible, for the aircraft’s EW system to electronically attack unanticipated radar threats. Advanced systems planned for Tempest and FCAS will be able to immediately download the required jamming waveforms from the combat cloud, and/or access up-to-date intelligence on radar threats as they appear during the sortie via the same route. 

While the FCAS and Tempest will have to face similar threats, their planned EW systems seem to follow different philosophies. Tempest will continue to use distinct radar, EW systems, and communications, whereas plans are more opaque for FCAS, although this aircraft could use technology developed via the pan-European CROWN (Combined Radar Communications Electronic Warfare Functions for Military Applications) initiative.

The Tempest’s mission system will receive data from the aircraft’s radar, EW systems, and communications, and this will be fused with other relevant data from onboard and offboard sensors to be presented to the pilot. Interestingly, it is planned the aircraft’s radar will perform electronic attack alongside its standard tasks, a concept which is being pioneered by Leonardo’s ECRS Mk.2 radar destined to be retrofitted to upgraded RAF Eurofighter Typhoon Tranche 3 fighters.

The European Union’s CROWN initiative aims to develop a Multifunction Radio Frequency Sensor (MRFS) combining radar, EW, and communications functions. The project involves seven EU nations and 11 organisations across the union. Launched in July 2021, the project is planned to run for 30 months, concluding in January 2024. 

CROWN’s goal is to develop a prototype MRFS to perform all these tasks with a single architecture which will help reduce the size, weight, and power (SWAP) demands of previous separate RF systems. 

SWAP is an important consideration in the design of all military platforms, in particular combat aircraft. CROWN plans to develop this MRFS architecture to Technology Readiness Level-4 (TRL-4) which will see it demonstrated in a laboratory, but CROWN officials suggested to ADBR that there is potential for MRFS to transition to TRL-7 beyond the initial project’s duration later this decade. 

This timetable chimes with the FCAS’s development which should be moving towards the prototype stage by then. Depending on the maturity of the MRFS architecture, it would not be surprising if some or all of it is incorporated into the FCAS, and it is noteworthy that several countries involved in CROWN – France, Germany, and Spain – are also FCAS partners.

RISKS
But MRFSs for sixth-generation combat aircraft – while attractive given their SWAP economisation – are not risk-free. They will be required to handle huge amounts of incoming and outgoing data to fulfil sensor, EW, and communications tasks which will require very high-powered processors notes Professor David Stupples, senior research fellow in satellite reconnaissance and surveillance, at the London Space Institute. 

Therefore, artificial intelligence and machine-learning (AI/ML) approaches will be integral to MRFS processing, and will be required to strike a careful balance of enhancing the pilot’s situational awareness while avoiding data deluge in the cockpit. Allied to the use of AI/ML are cognitive radar, EW, and communications methodologies which will need to form part of the MRFS’s processing, because the architecture will need to continually adapt to the – likely heavily-contested – electromagnetic environment. 

Antenna design is another consideration. The advent of Active Electronically Scanned Arrays (AESAs) in the 1990s opened a world of possibilities in the radar domain, but the arrays that MRFSs will require will need to take AESA a step further. A combat aircraft’s radar, EW, and communications systems must all transmit and receive a myriad of different frequencies, and antennas are of disparate shapes and sizes precisely because of the different tasks they perform. 

For example, radars and EW systems make highly-directional transmissions, as these need to go to a specific target, but communications transmissions are often omni-directional. Morphing antennas which can physically change their shape to accommodate the frequencies they are transmitting and receiving offer one possibility. But, how practical would such technology be to install and use in a combat aircraft? 

The FCAS and Tempest will both show the direction of travel regarding future advanced radar, EW, and communications system architectures. Their RF subsystems will include levels of sophistication eclipsing what is possible today, and what has been envisaged in the past. This is just as well because these aircraft will be flying and fighting in heavily electromagnetically contested environments, the likes of which the world has never seen. 

This article appeared in the Sept-Dec 2021 issue of ADBR.