A mooted plan for the US to buy S-400 SAM systems from Turkey could prompt a ELINT bonanza.
Senator John Thune, a Republican Senator from South Dakota has proposed that the US purchase the Almaz-Antey S-400 (NATO reporting name SA-21 Growler) long-range/high-altitude Surface-to-Air Missile (SAM) systems that Turkey procured from Russia.
In 2017 Turkey procured two S-400 systems, a total of four battalions, for $2.4 billion with deliveries commencing in 2019. This threw a spanner in the works of plans by the Türk Hava Kuvvetleri (THK/Turkish Air Force) to acquire Lockheed Martin F-35A Lightning-II combat aircraft.
A total of 120 aircraft were expected to be acquired before the acquisition was cancelled by the administration of President Donald Trump in July 2019. The administration was concerned that the S-400’s sensors, principally its ground-based air defence and fire control radars, could collect sensitive information regarding the F-35A’s radar cross section and electromagnetic emissions.
The cancellation of the acquisition resulted in the four THK F-35As delivered to Luke airbase, Arizona, being rerolled to furnish the US Air Force.
Nyet from Moscow
Mr. Thune suggested that the US acquisition of both S-400 systems would remove them from Turkey and hence THK control allowing F-35A deliveries to continue. Russian lawmakers protested the proposal with Leonid Slutsky, chair of the Russian Duma (parliament) committee on international affairs, condemning Mr. Thune’s proposal as “unprincipled and cynical.”
It seems unlikely that such a purchase will occur in the near term. Such a move by Ankara would make Moscow hopping mad. Yet such a purchase by the US would offer serious benefits.
Aside from resuming F-35A deliveries to Turkey, it would give the United States Air Force, and US armed forces in general, once of the world’s most advanced air defence systems to pour over at their leisure.
The US Department of Defence already possesses a smorgasbord of Soviet-era SAMs and ground-based air surveillance and fire control/ground-controlled interception radars. These have been sourced from a myriad of ex-Warsaw Pact countries. They are routinely used to provide realistic threats during US-based international air exercises like Red Flag.
The US Navy and USAF are both overhauling their Suppression/Destruction of Enemy Air Defence (S/DEAD) postures. The US Navy is deploying the Boeing EA-18G Growler electronic warfare and S/DEAD aircraft, along with Northrop Grumman’s AGM-88E Advanced Anti-Radar Guided Missile, a variant of the venerable AGM-88 HARM (High Speed Anti-Radar Missile) family. The US Air Force is optimising the F-35A to perform S/DEAD using Northrop Grumman’s AGM-88F HCS (HARM Control System) AGM-88 variant.
US and allied aircraft operating over Syria have flown in airspace thought to be protected by the S-400. Russia has deployed two systems to the northwest of the country since 2015.
However, there is doubt in some quarters of the NATO electronic warfare community as to whether either system has been activated in full for fear that Electronic Intelligence (ELINT) regarding their 91N6 (NATO reporting name Big Bird) S-band (2.3 gigahertz/GHz to 2.5GHz/2.7GHz to 3.7GHz) and 96L6E (NATO reporting name Cheese Board) C-band (5.25GHz to 5.925GHz) early warning and target acquisition radar could be hoovered up by US and NATO ELINT aircraft.
For all intents and purposes much of the S-400’s design and capabilities remain a mystery. No wonder Moscow is nervous about NATO getting its hands on a couple.
The People’s Republic of China has made grandiose claims for the performance of its JY-27A ground-based air surveillance radar. They should be treated with caution.
An article published in the Global Times, an offshoot of the
People’s Daily, itself a mouthpiece for the People’s Republic of China’s ruling
Communist Party, claimed on 28 May that the country’s new CETC JY-27A Very High
Frequency (VHF: 30 megahertz/MHz to 300MHz) can detect aircraft with a low
Radar Cross Section (RCS). The article said that, not only can the radar detect
such aircraft, but can “guide missiles to destroy them.”
Low frequency radars detecting low
RCS aircraft is not a new claim. This principle has been known for decades and
has already been exploited in radars like Russia’s NNIIRT 1L119 Nebo-SVU VHF system. The
long wavelength signals transmitted by VHF radars have meant that while low-RCS
aircraft maybe detectable, they may not be detectable with the sharp precision
required to guide an Air-to-Air Missile (AAM) or Surface-to-Air Missile (SAM)
to its target. Put simply, this is why many fighter radars, ground- and
ship-based fire control radars and missile radar seekers transmit in
frequencies from X-band (8.5 gigahertz/GHz to 10.68GHz) and above. What these
radars lose in detection range, compared to lower frequency radars, they make
up for in precision. The Global Times article
claimed that Chinese radar engineers have solved this precision deficit by
networking together several radars positioned a known distance from one
another, looking at the same patch of sky in different directions to determine an
aircraft’s location. Once detected it could be possible to guide “long-range
anti-aircraft missiles” to perform precision strikes on these targets.
Distributed, networked radars to
counter stealth is an established concept. The electronic warfare and radar
expert Dr. Carlo Kopp discussed this approach in his seminal 2012 article in Defence Today entitled ‘Advancing
Counter-Stealth Radar Technology’. He asserted that “Defeating stealth targets
using networking and data fusion presupposes that some radars can see the
target some of the time, also that the target’s stealth is considerably poorer
in some directions compared to others, and finally that the target is visible
to radars from varying aspects.” Basically, a low RCS aircraft may have a low
radar signature when viewed from head on, of from a particular angle but not an
equally low signature in all directions. By scattering and networking several
antennas across a wide area, one of the antennas may get a lucky glimpse of
part of the aircraft which is not so stealthy and thus detect it. Dr. Kopp adds
that for this to be effective, the non-stealthy part of the aircraft needs to
be visible to that particular radar for some time. An aircraft flying into hostile
airspace is unlikely to hang around and may be travelling at very high speeds,
thus only exposing itself to the radar for a very short time. To further
complicate matters, aircraft such as the US Air Force’s Northrop Grumman B-2A
Spirit strategic bomber and Lockheed Martin F/A-22A Raptor air superiority
fighter use ‘all-aspect’ RCS reduction techniques. This means that they are
stealthy regardless of the angle from which they are viewed by radar. Future US aircraft, such as the forthcoming
Northrop Grumman B-21 Raider strategic bomber are likely to have even better RCS
reduction design configurations.
Dr. Kopp concedes that “a networked
data fusion system (fusing data from several distributed radars) is thus not a
panacea, but is potentially quite effective against stealth designs that do not
have genuine ‘all aspect’ stealth capability.” There is an additional problem.
Airframe limitations mean that low-RCS aircraft cannot be designed to defeat
all radar transmission wavelengths. Instead, airframes are optimised to defeat
the radar systems most likely to be used for the precision detection of such a
target and for fire control. This typically includes radars transmitting in
S-band (2.3GHz to 2.5GHz/2.7GHz to 3.7GHz) and above. To summarise, a network
of VHF radars maybe capable of detecting an aircraft with a low RCS but lacking
all-aspect stealth, yet weapons still have to be guided with precision to the
target. This is where a fighter aircraft’s X-band radar would come into play,
or the guidance radars and radar seekers used by AAMs or SAMs transmitting in
X-band and above. These are precisely the frequencies that low-RCS aircraft are
designed to defeat. Networked VHF radars may give you a good fix on where the
aircraft is in the sky, but the missile’s end game still depends on higher
frequency radars which stealth aircraft are designed to outfox.
Arguably this could be overcome by a
salvo launch of SAMs and AAMs into the area of sky where the aircraft is
thought to be. This might not be done with too much precision, but a load of
missiles could be launched ballistically with the hope of scoring a lucky hit. It
could prove an expensive tactic as it would potentially waste missiles at an early
stage of a conflict, the moment when low-RCS aircraft are most likely to be
Moreover, these VHF radars, and fire
control radars operating in higher wavebands would almost certainly be
subjected to heavy electronic attack at the outset of a conflict. Aircraft such
as the F/A-22A, B-2A, B-21 or Lockheed Martin’s F-35A/B/C Lightning-II fighters
would be accompanied by jamming platforms like the US Navy’s E/A-18G Growler
aircraft as they fly into contested airspace. The Block-2 Low Band Jammer (LBJ)
segment of the latter aircraft’s Next Generation Jammer, which replaces its
current Harris AN/ALQ-99 tactical jamming system, is thought to cover a
waveband of 100 megahertz to two gigahertz. The US Navy is currently selecting
a vendor for the Block-2 LBJ with a team comprising Northrop Grumman and
Harris, and L3 vying for selection. While VHF radars like the JY-27A maybe
trying to detect low RCS aircraft, they will be a prime target for both escort
and stand-off jamming for aircraft like the E/A-18G. They will also be high
priority targets for kinetic weapons. Given the frequencies they use, VHF
radars tend to be big. In the case of the JY-27A PRC officials have hinted that
several radars are required to detect low RCS aircraft. Such targets could show
up well on aerial reconnaissance imagery. They also need to transmit, and once
transmitting, will reveal their position to ELINT (Electronic Intelligence)
gathering assets such as the US Air Force’s Boeing RC-135U Combat Sent
aircraft. Once their position is betrayed, electronic and kinetic attack can be
brought to bear.
The PRC maybe feeling emboldened by the development of the JY-27A and its touted capabilities. The death of low RCS airframe design has been predicted umpteen times since the B-2A and Lockheed Martin F-117A Nighthawk ground attack aircraft debuted in service in 1997 and 1983 respectively. The possible shortcomings of such radars are no excuse to be complacent, and such systems should be high priority electronic and kinetic targets at the start of any conflict. The JY-27A’s attributes may be accompanied with a healthy serving of hyperbole, but that is no excuse for complacency.
India might need a new electronic warfare system to accompany its NGARM anti-radar missile.
A senior source close to the Indian Air Force (IAF) Electronic Warfare (EW) community has told chainhomehigh that the force may need an emitter locator system to accompany its forthcoming New Generation Anti-Radiation Missile (NGARM). This new weapon, which performed flight tests from an IAF Sukhoi Su-30MKI fighter on 18 January, is under development. It represents a step change for the IAF’s Suppression of Enemy Air Defence (SEAD) posture and could enter service in the next five years.
An emitter locator system would be an
important addition to hone the weapon’s accuracy. SEAD aircraft such as the US
Air Force’s Lockheed Martin F-16CJ Viper Weasel and the Luftwaffe/Aeronautica
Militaire (German and Italian Air Force) Panavia Tornado-ECR jets use
Raytheon’s AN/ASQ-213 HARM (High Speed Anti Radiation Missile) and ELS (Emitter
Location System) respectively. These provides highly precise targeting
coordinates for the aircraft’s Raytheon AGM-88B/C/E HARMs though the
geolocation of ground-based air surveillance and fire control/ground controlled
interception radars using those radars’ emissions. Both systems are thought to
cover a waveband of 0.5 megahertz to 20GHz encompassing the majority of the
wavebands used by these radars. The ability of the AN/ASQ-213 and ELS allow the
missiles to target low-band ground-based air surveillance radars routinely used
to detect aircraft with a low radar cross section. Both the AN/ASQ-213 and the
ELS are though to have a residual role collecting electronic Intelligence. This
can be either recorded for later analysis or shared with other platforms to
enable near-real time off-board kinetic or electronic attack to be directed
against such targets.
While aircraft configured to deploy
the AGM-88 series can do so without a locator system, the addition of the
latter significantly sharpens the aircraft’s accuracy vis-à-vis the threat. It also enables threat prioritisation, and
multiple threats to be engaged in a rapid sequence. This is important as it
moves a platform beyond simply using an anti-radiation missile for
self-protection, by which it will fire the weapon using the threat information
presented by its radar warning receiver. Instead, an emitter locator system
allows the aircraft to be used as a SEAD platform engaged in the identification
and roll-back of an adversary’s ground-based air defences at the tactical
and/or operational levels. The IAF is no stranger to SEAD. For example, it performed
such missions against ground-based air surveillance radars located at Badin in
southwest Pakistan during India’s 1965 war with the latter using
English Electric Canberra-B Mk.56 medium bombers.