Analysis: Wishful Thinking

Forthcoming USAF platforms such as the B-21 Raider strategic bomber maybe yet more resistant to radar detection than present day low-RCS platforms (USAF)

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.

Networked Radars

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 used.

Jamming

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.

Conclusions

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.

South Korea – New IFF Transponder

The Republic of Korea has awarded a contract to Telephonics Corporation for the integration of the company’s AN/UPX-44 Identification Friend or Foe (IFF) transponder onto undisclosed ground-based air surveillance radars operated by the country.

The AN/UPX-44 can work with the United States’ Next Generation Air Transportation System’s Automatic Dependent Surveillance Broadcast (ADS-B) air traffic management architecture, along with Mark XIIA IFF Mode-5 and Mode-S military and civilian transponders.

There is no word regarding which radars will be equipped with the AN/UPX-44 IFF, the value of the contract, how many systems will be delivered or when deliveries will commence and complete.

India – Akash Deployment

Lohegaon Air Force Station which is collocated with Pune Airport on the west coast of India is due to receive Defence Research and Development Organisation (DRDR) Akash medium-range Surface-to-Air Missiles (SAMs) to protect the base against air attack.

The Indian Air Force (IAF) facility at Lohegaon is home to two Sukhoi Su-30MKI squadrons; namely 20 and 30 Squadrons of 2 Wing, nicknamed ‘Lightning’ and ‘Rhinos’ respectively. The Sukhois form a key component of the IAF’s strike and air defence force.

The induction of the first Akash squadron is expected to occur in a few months, according to Air Commodore Vivek R. Chaudhari, commanding officer of the Lohegaon base. An Akash squadron includes two batteries. Each battery comprises three missile launch vehicles, a command post and a passive phased-array Rajendra radar. This radar’s C-band surveillance radar can track up to 64 targets and simultaneously engage four. Engagements are controlled by the Rajendra’s X- and Ku-band antenna. At the squadron level, a Rohini S-band radar performs surveillance tracking targets at a range of up to 180km (97nm) and 59,000ft (17,983m). The missiles have a range of around 35km (19nm), and can engage targets at 59,055ft (18.000m) altitude.

The news of the Akash deployment to Lohegaon follows the delivery of the first Akash units to the IAF this March.

Taiwan – Second-hand News?

The Taiwanese government has abandoned plans to procure a second modified Raytheon AN/FPS-115 PAVE PAWS air surveillance radar from the United States.

The Ultra High Frequency AN/FPS-115 operates in the 420-450 megahertz range, and is said to be capable of detecting incoming ballistic missiles at a range of circa 4,827km (2,606nm).

In February 2004 the US Department of Defense notified Congress of its intention to sell Taiwan two of these radars for a total of €1.4 billion ($1.8 billion). A single radar was then purchased from Raytheon via the US Air Force in June 2005 for €583 million ($752 million). This radar was then installed at Loshan Mountain in northern Taiwan, where testing commenced in November last year.

Reports surfaced in late September from the Agence France Presse news agency that plans to procure a second radar had been abandoned by the country’s Defense Minister Kao Hua-chu, according to a spokesperson from the Taiwanese Air Force. So far including its procurement, installation and preparation the radar at Loshan is said to have cost €930 million ($1.2 billion).

The Agence France Presse report went on to note that an additional €105 million ($136 million) has been requested by the contractor to complete the installation at Loshan. These funds have been requested for maintenance, and additional research and development for the radar. The total costs of the radar so far, including the recent payment request, now total an estimated €1 billion ($1.4 billion).

The sums spent on the purchase of the radar, its construction and its testing have been the cause of political controversy in Taiwan, with members of the Taiwanese parliament’s defence committee criticising the amount of money spent so far.

However, a report in the Taipei Times on 1st October cited the C4ISR Journal and a report by the US Congressional Research Service noting that plans to acquire the second radar had actually been abandoned back in 2007.

Regardless of when the decision was made to abandon this procurement plans, it seems that for now Taiwan will have to rely on its single AN/FPS-115 to provide ballistic missile early warning over the north of the island.

China – New Air Defence Warship

China’s People’s Liberation Army Navy (PLAN) intends to develop a new air-defence guided missile destroyer (DDG), it was announced in early September.

These new ships will carry a pair of 32-round vertical missile launch systems, capable of deploying the CPMIEC HQ-9 Surface-to-Air Missile (SAM). This medium/high altitude weapon uses active radar homing, has a ceiling of circa 98,400ft (30km), and a range in the region of 200km (124nm). These SAMs are already used on the PLAN’s ‘Type-52C’ class DDGs.

The new ‘Type-52D’ class vessels will be equipped with a Type-346 Active Electronically Scanned Array (AESA) and Type-518 L-band air/sea surveillance radar.

The Type-346, which is already in service on China’s ‘Type-52C’ class ships, is believed to have a range of up to 160km (86nm). Meanwhile, the Type-518 system is capable of rapid frequency shifting, has low sidelobes and electronic counter-counter measure protection.

There is no word on when construction of the Type-52D DDGs could commence, or how many ships are likely to be included in the class.

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