October 14, 2017
Ever since the development of stealth technology for aircraft, many different systems have been advertised as “stealth killing.” One of the more innovative solutions is the Russian Struna-1/Barrier-E bistatic radar system developed by NNIIRT, a division of the Almaz-Antey Joint Stock Company. Almaz-Antey is the premier air-defense and radar manufacturer in Russia; they make the Tor, Buk and S-400 anti-aircraft systems, as well as their respective search radars. The Struna-1 was originally developed in 1999. A further evolution of Struna-1, the Barrier-E system was later showcased for export at MAKS 2007. While it is not part of Almaz-Antey’s online catalog, it was shown alongside other radars at MAKS 2017. The system is rumored to be deployed around Moscow.
The Struna-1 is different than most radars in that it is a bistatic radar, meaning it relies on the receiver and transmitter of the radar to be in two different locations as opposed to conventional radar technology where the receiver and transmitter are located in the same location. Normal radar systems are limited by the inverse fourth power law. As the radar target goes further away from the transmission source, the strength of the radar signal decays as per the regular inverse square law. However, radar detection works by receiving reflections of the radar signal. With a conventional radar, this results in the received signal being four times weaker than that put out. Stealth works because at a distance, an aircraft can mitigate its radar returns to be small by scattering them and absorbing them using radiation-absorbent materials. This degrades the quality of the radar track so it is harder to distinguish precise information about an aircraft.
The Struna-1 solves this problem by positioning the transmitter in a different location than the receiver. The link between the transmitter and receiver has increased power relative to a conventional radar, as it falls off according to the inverse square law as opposed to the inverse fourth power law. This allows the radar to be more sensitive, as it is effectively acting as a radar tripwire. According to Russian sources, this setup increases the effective radar cross section (RCS) of a target by nearly threefold, and ignores any anti-radar coatings that can scatter the radio waves. This allows the detection of not only stealth aircraft, but other objects with low RCS such as hang gliders and cruise missiles. As many of ten receiver/transmitter tower pairs—each tower is called Priyomno-Peredayushchiy Post (PPP) in Russian publications—can be placed. Sources vary in potential configurations of the towers, but the maximum span between two single towers is 50km. This leads to a maximum theoretical perimeter of 500km.
These individual towers have relatively low power consumption, and they do not emit as much energy as traditional radars, making them less vulnerable to anti-radiation weapons. The towers are mobile, allowing for forward deployment in times of conflict. They rely on microwave data links to communicate with each other and a centralized monitoring station, which can be located at a significant distance from the system. The distributed nature also allows the system to keep operating if one node goes down, albeit with less precision. The low height of the transmitter and receiver towers (only 25m off the ground) make Struna-1 very good at detecting low altitude targets, a target set that conventional radars often have trouble with.
Limitations of the Struna-1 include a low detection altitude. The nature of the system results in the detection range being a rough biased parabola between the receiver and transmitter. This limits the detection altitude to around 7km at the tallest point, with the maximum detection range going down as one gets closer to the transmitter/receiver towers. The transverse size of the detection zone is likewise limited, being around 1.5km close to the towers to 12km at the optimal point between the towers. The small size of the detection zone limits the use of the Struna-1 system as a tripwire, it cannot replace traditional radars as an overall search mechanism. However with its high precision tracks of stealthy aircraft, it would serve as a good counterpart to other longer-band radar systems such as Sunflower, which provide less precise tracks of planes. The Struna-1 cannot act as a targeting radar due to its inability to provide constant radar illumination tracking a target, so it cannot be used to guide in semi-active surface-to-air missiles.
While the Struna-1 bistatic radar is not a be-all end-all detection solution for stealth aircraft, it could pose a significant threat to stealth NATO aircraft in a future conflict. Strike aircraft with stealth features are particularly vulnerable, the strike role tends to favor flight profiles that might cause aircraft to fly into the Struna-1’s detection range. In tandem with other modern “stealth-defeating” radar systems, the Struna-1 could provide critical information to an adversary on the position and movement of stealth aircraft.
Source: National Interest “How Russia Is Trying to Make America’s F-22 and F-35 as Obsolete as Battleships”
Note: This is National Interest’s article I post here for readers’ information. It does not mean that I agree or disagree with the article’s views.
Quite a few high-ranking officers, politicians and military experts give me the impression that when they make comparison between the weapons of similar kind developed by different nations, they regard the weapons as toys instead of what a country relies on for its national security.
When the US designed its F-22 and F-35, it assumes that others have no stealth fighter so that its stealth fighter jet may shoot down enemy fighter jet with missile before the enemy is even able to detect its stealth fighter. Therefore, more attention was paid to stealth than the fighter jet’s maneuverability in dogfight.
Moreover, US military strategy focuses on break enemy’s anti-access/area denial (A2/AD) as the US regards attacking and subduing its enemy as the key to its national security. As a result, US stealth fighter jets shall be capable of penetrating enemy air defense and be equipped with air-to-ground weapons.
China, however, develops its stealth fighter J-20 to resist enemy attack so that it regards as the key J-20’s capability to grab air supremacy from others’ stealth fighters. If a J-20 and its enemy flies at the speed Mach 2, it has only 2.3 minutes before the two meet suppose that their radar is good enough to discover enemy stealth fighter 150 km away. Suppose J-20’s missiles go at Mach 4, it takes 1.5 minutes for the pilots to find that their missiles fail to hit. Then they have only 0.8 minutes left not enough for a second missile attack. Therefore, J-20 must have better dogfight capabilities than F-22 and F-35 as of all the countries in the world only the US F-22 and F-35 are designed with the capabilities to break other countries’ A2/AD and to attack their homeland.
That is why China is satisfied with its J-20 in spite of the radar visibility from its back and its lack of the capability to penetrate enemy air defense. Analysts may be happy that J-20 is inferior to F-22 and F-35 in those respects but neglect J-20’s capabilities in grabbing air supremacy.
However, US military is not so carried away by their analysis as to risk attacking China with F-22 and F-35. They want to develop B-21 to attack China.
Now, there is news that new J-20s use better engines with radar invisibility from their back and greater vector thrust. The analysts shall not be unhappy as J-20 is utterly incapable of attacking US homeland even if it is capable of penetrating enemy air defense.
Article by Chan Kai Yee
Some people boast F-35’s network function to share information with other F-35s and believe F-35s can penetrate China’s air defense by J-20 that is designed to dominate Chinese airspace. I have pointed out in my previous post that for J-20 network with its ground command center is much more important as there is China’s supercomputer there to analyze information not only from J-20s but also China’s ground and navy’s air defense system and give instruction to J-20s to hit F-35s before F-35s have enough time to analyze the information from their network.
F-35’s computer is but a child’s toy compared with the supercomputer in China’s ground command center.
Now, US military expert Bill Gertz’s article “Chinese supercomputers threaten U.S. security” on May 3, not only confirms my opinion but even quotes a recent report of joint National Security Agency-Energy Department study as saying, “China is eclipsing the United States in developing high-speed supercomputers used to build advanced weapons, and the loss of American leadership in the field poses a threat to U.S. national security.”
Now, its Chinese supercomputers that threaten the US instead F-35s threatening China!
“Supercomputers play a ‘vital role’ in the design, development and analysis of almost all modern weapons systems, including nuclear weapons, cyberwarfare capabilities, ships, aircraft, communications security, missile defense, precision-strike capabilities and hypersonic weapons, the report said.”
Comment by Chan Kai Yee on Washington Times’ report, full text of which can be viewed at http://www.washingtontimes.com/news/2017/may/3/china-supercomputers-threaten-us-security/.
According to a vice chairman of Russia’s State Duma, Russia has already delivered to China first batch of S-400 air defense missile systems.
S-400 is Russia’s best air defense system, which due to confidentiality is allowed to be sold only to countries very close to Russia. India and Turkey are queuing for purchase of the system.
This blogger’s comment: Russia has contract obligation to begin delivery of S-400 by 2018. The earlier delivery perhaps aims at helping China deal with US F-35s that are being deployed in East Asia. S-400 has a range of 150 km to hit stealth aircraft.
Source: Interfax “Russia high official: First batch of S400 air defense missile system has been delivered to China” (summary by Chan Kai Yee based on the report in Chinese)
Dave Majumdar February 20, 2017
With a missile warhead large enough, the range resolution does not have to be precise. For example, the now antiquated S-75 Dvina—known in NATO parlance as the SA-2 Guideline—has a 440-pound warhead with a lethal radius of more than 100 feet. Thus, a notional twenty-microsecond compressed pulse with a range resolution of 150 feet should have the range resolution to get the warhead close enough—according to Pietrucha’s theory. The directional and elevation resolution would have to be similar with an angular resolution of roughly 0.3 degrees for a target at thirty nautical miles because the launching radar is the only system guiding the SA-2. For example, a missile equipped with its own sensor—perhaps an infrared sensor with a scan volume of a cubic kilometer—would be an even more dangerous foe against an F-22 or F-35.
The United States has poured ten of billions of dollars into developing fifth-generation stealth fighters such as the Lockheed Martin F-22 Raptor and F-35 Joint Strike Fighter. However, relatively simple signal processing enhancements, combined with a missile with a large warhead and its own terminal guidance system, could potentially allow low-frequency radars and such weapons systems to target and fire on the latest generation U.S. aircraft.
It is a well-known fact within Pentagon and industry circles that low-frequency radars operating in the VHF and UHF bands can detect and track low-observable aircraft. It has generally been held that such radars can’t guide a missile onto a target—i.e. generate a “weapons quality” track. But that is not exactly correct—there are ways to get around the problem according to some experts.
Traditionally, guiding weapons with low frequency radars has been limited by two factors. One factor is the width of the radar beam, while the second is the width of the radar pulse—but both limitations can be overcome with signal processing.
The width of the beam is directly related to the design of the antenna—which is necessarily large because of the low frequencies involved. Early low-frequency radars like the Soviet-built P-14 Tall King VHF-band radars was enormous in size and used a semi-parabolic shape to limit the width of the beam. Later radars like the P-18 Spoon Rest used a Yagi-Uda array—which were lighter and somewhat smaller. But these early low frequency radars had some serious limitations in determining the range and the precise direction of a contact. Furthermore, they could not determine altitude because the radar beams produced by these systems are several degrees wide in azimuth and tens of degrees wide in elevation.
Another traditional limitation of VHF and UHF-band radars is that their pulse width is long and they have a low pulse repetition frequency [PRF]—which means such systems are poor at accurately determining range. As Mike Pietrucha, a former Air Force an electronic warfare officer who flew on the McDonnell Douglas F-4G Wild Weasel and Boeing F-15E Strike Eagle once described to me, a pulse width of twenty microseconds yields a pulse that is roughly 19,600 ft long—range resolution is half the length of that pulse. That means that range can’t be determined accurately within 10,000 feet. Furthermore, two targets near one another can’t be distinguished as separate contacts.
Signal processing partially solved the range resolution problem as early as in the 1970s. The key is a process called frequency modulation on pulse, which is used to compress a radar pulse. The advantage of using pulse compression is that with a twenty-microsecond pulse, the range resolution is reduced to about 180 feet or so. There are also several other techniques that can be used to compress a radar pulse such as phase shift keying. Indeed, according to Pietrucha, the technology for pulse compression is decades old and was taught to Air Force electronic warfare officers during the 1980s. The computer processing power required for this is negligible by current standards, Pietrucha said.
Engineers solved the problem of directional or azimuth resolution by using phased array radar designs, which dispensed with the need for a parabolic array. Unlike older mechanically scanned arrays, phased array radars steer their radar beams electronically. Such radars can generate multiple beams and can shape those beams for width, sweep rate and other characteristics. The necessary computing power to accomplish that task was available in the late 1970s for what eventually became the Navy’s Aegis combat system found on the Ticonderoga-class cruisers and Arleigh Burke-class destroyers. An active electronically scanned array is better still, being even more precise.
With a missile warhead large enough, the range resolution does not have to be precise. For example, the now antiquated S-75 Dvina—known in NATO parlance as the SA-2 Guideline—has a 440-pound warhead with a lethal radius of more than 100 feet. Thus, a notional twenty-microsecond compressed pulse with a range resolution of 150 feet should have the range resolution to get the warhead close enough—according to Pietrucha’s theory.
The directional and elevation resolution would have to be similar with an angular resolution of roughly 0.3 degrees for a target at thirty nautical miles because the launching radar is the only system guiding the SA-2. For example, a missile equipped with its own sensor—perhaps an infrared sensor with a scan volume of a cubic kilometer—would be an even more dangerous foe against an F-22 or F-35.
Dave Majumdar is the defense editor for the National Interest. You can follow him on Twitter: @davemajumdar.
Source: National Interest “Stealth-Killer: How Russia or China Could Crush America’s F-35 or F-22 Raptor”
Note: This is National Interest’s article I post here for readers’ information. It does not mean that I agree or disagree with the article’s views.
According to National Interest’s article by Dave Majumdar on February 10, 2017, a report of the Center for Strategic and Budgetary Assessments (CSBA) commissioned by US Navy says that the US has to develop a new stealth manned fighter to contend for air superiority with China’s J-20.
The article says, “The F/A-18E/F Super Hornet and the Lockheed Martin F-35C Joint Strike Fighter—which are not dedicated air superiority fighters—would not be suitable to defeat advanced adversary air defenses or enemy aircraft such as the Chengdu J-20 or other Chinese fifth-generation warplanes. ‘In contrast to today’s multimission strike-fighters, such as the F-35C, the design of these aircraft would need to focus mostly on the fighter mission rather than strike, so that they would have the speed, endurance, maneuverability, and air-to-air sensor capability needed for counter-air operations,’ the report states.”
That is only natural because when the US began developing F-35, no other country has stealth fighter to contend for air supremacy with F-35, therefore there is much more emphasis on F-35’s capabilities in penetrating enemy air defense to attack enemy targets on land or at sea.
Now, China has developed J-20 specially for grabbing air supremacy from US stealth fighters. The US finds it in a poor position and is in dire need for some fighters to deal with J-20. Sad for US Navy. No worry, US Navy can ask Congress for lots of funds to develop new stealth fighters for air superiority.
The problem is that China is also spending a lot in developing fighter jets superior to US ones and so is Russia. The US has to conduct arms race in earnest with both Russia and China.
Usually, at least one of the two countries competing with the US may develop something better than US ones. If it is China, US will lose the arms race. However, if it is Russia, the US will also lose to China as Russia is willing to sell and China can afford the purchase of Russia’s best fighter jets as proved by its purchase of Russia’s so far the best fighter jet Su-35.
Comment by Chan Kai Yee on National Interest’s article, full text of which can be viewed at http://nationalinterest.org/blog/the-buzz/the-us-navy-needs-new-fighter-russia-china-are-blame-19409.
When the US wanted China to respect Hague arbitration ruling to give up China’s rights and interests in the South China Sea, Chinese troops conducted its largest drill there and Chinese navy chief pointed his finger at his US counterpart in his talks with him. Soon afterwards Chinese air force began to conduct combat patrol in the South China Sea especially on the disputed Scarborough Shale.
Now, Reuters says in its report “Trump nominee says China should be denied access to South China sea islands”, “U.S. President-elect Donald Trump’s nominee for secretary of state set a course for a potentially serious confrontation with Beijing on Wednesday, saying China should be denied access to islands it has built in the contested South China Sea.”
What does that mean?
It means the nominee Rex Tillerson wants a real war instead of trade war with China.
The US is preparing for that as it has been sending a squadron of F-35, its most advanced fighter jets, to Japan for the war.
China is not less prepared as it has been stepping up the development, production and deployment its most advanced fighter jet J-20s so that if the US hurts China’s core interests of its rights and interests in the South China Sea, China has to fight. The Chinese ruling party the CCP will become extremely unpopular if it is afraid to fight.
We hope it will be a limited war between the two powers as the US cannot send its army to invade China given China’s huge modern army and US experience of defeat in Korean War. China, on the other hand, is utterly unable to send its army to the US.
China is now able to win the naval war as China’s J-20 is superior to F-35 in a war of defense and China can sink US aircraft carriers with saturate attack of its large number of anti-ship ballistic and cruise missiles.
What will follow then? Attack China with nuclear weapons in retaliation? That will be the end of human race.
Do Trump and his nominee Rex Tillerson want that?
Let’s hope that Rex Tillerson’s hardline statement is but rhetoric.
Comment by Chan Kai Yee on Reuters’ report, full text of which is reblogged below:
Trump nominee says China should be denied access to South China sea islands
By David Brunnstrom and Matt Spetalnick | WASHINGTON January 11, 2017
U.S. President-elect Donald Trump’s nominee for secretary of state set a course for a potentially serious confrontation with Beijing on Wednesday, saying China should be denied access to islands it has built in the contested South China Sea.
In comments expected to enrage Beijing, Rex Tillerson told his confirmation hearing before the U.S. Senate Foreign Relations Committee that China’s building of islands and putting military assets on those islands was “akin to Russia’s taking Crimea” from Ukraine.
Asked whether he supported a more aggressive posture toward China, he said: “We’re going to have to send China a clear signal that, first, the island-building stops and, second, your access to those islands also is not going to be allowed.”
The former Exxon Mobil Corp (XOM.N) chairman and chief executive did not elaborate on what might be done to deny China access to the islands it has built up from South China Sea reefs, equipped with military-length airstrips and fortified with weapons.
Tillerson also said Washington needed to reaffirm its commitment to Taiwan, which Beijing regards as a renegade province, but stopped short of Trump’s questioning of Washington’s long-standing policy on the issue.
“I don’t know of any plans to alter the ‘one China’ position,” he said.
Tillerson said he considered China’s South China Sea activity “extremely worrisome” and that it would be a threat to the “entire global economy” if Beijing were able to dictate access to the waterway, which is of strategic military importance and a major trade route.
He blamed the current situation on what he termed an inadequate U.S. response. “The failure of a response has allowed them just to keep pushing the envelop on this,” Tillerson said.
“The way we’ve got to deal with this is we’ve got to show back up in the region with our traditional allies in Southeast Asia,” he said.
Democratic President Barack Obama’s administration conducted periodic air and naval patrols to assert the right of free navigation in the South China Sea. These have angered Beijing, but seeking to blockade China’s man-made islands would be a major step further and a step that Washington has never raised as an option.
Tillerson’s words also went beyond Trump’s own tough rhetoric on China.
Obama has sought to forge a united front in Southeast Asia against China’s pursuit of its territorial claims, but some allies and partners who are rival claimants have been reluctant to challenge Beijing.
Tillerson called China’s South China Sea island-building and declaration of an air defense zone in waters of the East China Sea it contests with Japan “illegal actions.”
“They’re taking territory or control, or declaring control of territories that are not rightfully China’s,” he said.
Tillerson also said the United States could not continue to accept “empty promises” China had made about putting pressure on North Korea over that country’s nuclear and missile programs.
He said his approach to dealing with North Korea – which recently declared it is close to carrying out its first test of an intercontinental ballistic missile – would be “a long-term plan” based on sanctions and their proper implementation.
Asked if Washington should consider imposing “secondary sanctions” on Chinese entities found to be violating existing sanctions on North Korea, Tillerson said: “If China is not going to comply with those U.N. sanctions, then it’s appropriate … for the United States to consider actions to compel them to comply.”
He accused China of failing to live up to global agreements on trade and intellectual property, echoing past remarks by Trump, who has threatened to impose high, retaliatory tariffs on China. But Tillerson also stressed the “deeply intertwined” nature of the world’s two biggest economies.
“We should not let disagreements over other issues exclude areas for productive partnership,” he said.
(Reporting by David Brunnstrom and Matt Spetalnick; Editing by Jonathan Oatis)