YJ-27 anti-stealth radar

Yes, typing mistake.

Let me elaborate something further. Back in the eighties when concepts of stealth were being worked out, and all these arguments---that it would cost much more more in terms of resources to counter stealth---failed to account a new factor that was also arising in the Eighties.

It's called Moore's Law, from one of the founders of Intel Corp. Its states that computing power will double every 18 months. In other words, electronics and computing technologies have generational cycles measured in 1.5 years, yet military development projects lasts for several years, even decades, and equipment are expected to even last for a few decades. The F-22 was supposed to have a product cycle of 40 years.

This means if Moore's Law are applied to military electronics, the development of all things electronics would outpace the platform by several fold, and that a platform may even experience several generational changes in its electronics before the platform is retired or face its replacement. That means among other things, radar, IRST, passive sensors, networking, user interfaces, sensor fusion.

However, the platform's VLO measures may have targeted requirements against sensors of the same generation as the platform, but it is difficult even by foresight how future sensor systems would emerge and how they would perform.

"The latter has a measurement accuracy of 150m"

..Good greif, talk about easily spoofed,that's terrible descrimination. Consider the new OTH-SW Radar that just went online in Newfoundland can measure the pressure differential between oil moving in water currents and direct spill recovery teams to track it down from over 300 miles away. You can not even fly below Surface wave radar.....

Consider the kill radius of a large SAM is on the order of tens of meters, a barrage of SAMs would be enough to cover your error. Even if the target is not brought down, the shrapnel damage will make it less stealthy.

"Consider the kill radius of a large SAM is on the order of tens of meters, a barrage of SAMs would be enough to cover your error. Even if the target is not brought down, the shrapnel damage will make it less stealthy."


...Resorting to barrages of missles is counterproductive to the purpose of a missle in the first place. Show me a country relying on barrages of missles, and I'll point you to a country soon bankrupt....

You must be using a very low frequency to get that kind of imprecision, but on the other hand, the actual sweep volume must be huge.

These radars are only search radars. They are meant to cue other more precise radars or even EOS/IRSTs towards the target, systems that have actual fire control on them. 150m is much more than enough to cue other radars for this purpose. S-300 systems for example, have seperate search and fire control radars.

aren't those puppies suspectible to anti-radiation missiles?

better alternatives are develope more multistatic pairs.

btw if the steath plane uses non-resonant RAM material which uses ferrites particles suspended in epoxy to reduce reflectivity of surface.

This is frequency indepedent , so it doesn't matter is microwave or VHF.
this reduces the RCS at the expense of infrared sig.

VHF radar is better against resonant type of RAM material. but not much against non-resonant type.

lilzz said:

aren't those puppies suspectible to anti-radiation missiles?

better alternatives are develope more multistatic pairs.

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Not really. ARMs have a threshold. For example, the Chinese FT-2000 runs as low as 2 gigahertz. AGM-88 runs as low as 500 MHz. This YLC radar may even go lower than that, or even as I suspect, metric wave or VHF.



Would be very interesting if this thing is even decametric.

more on JY-27 type of radar. This is from air force engineering university newspaper regarding the usage of JY-27
- basically it seems like the idea is to use the wideband radar like JY-27 to guide the missiles to within 15km of the stealth target and hope that the missile can lock onto the stealth target using impulse? (maybe CW) seeker.

07年1月，《 空军工程大学学报：自然科学版 》
刊登了《中末制导交班半实物实验研究》的文章。
用半实物的模式验证了米波雷达+中末制导交班的可能性（保证末制导精度）。
透露米波雷达的任务就是把防空导弹送入目标区周边15km的范围。
联系到7年前同样是空军工程大学的一篇论文，大意是冲激体制末制导雷达反隐身技术。里面提到正在对此种导引头已经完成技术论证（97年开始），正在攻关研制阶段（很多关键器件当时中国还没有）。此文目前已经在论文库中不能下载（以前可以的，我有备份）。里面提到的数据，也就是说传统PD/单脉冲体制末制导头无法发现F22一类隐身目标（理论发现距离小于5km），当采用冲击雷达体制之后，末导头可以保持15-20km左右的对隐身非隐身飞机的发现距离。此后我就一直关注相关此弹此防空系统的研制状况。

因为此弹必须由可发现隐身飞机的雷达系统（如米波雷达）提供中继制导信号，因此100%可以确认此反隐身战机的防空弹制导头已经进入工程高级研发阶段（尾声），准备投入实际打靶试验了。

对付F22的杀手锏又多了一个。我在虚幻空版上很早就提到了此弹，一直在等其的消息。今天终于等到了。大家赶快庆贺一下...
由此预计此弹最晚在2011年可以进入部队服役...（此论文写作时间至少是06年上半年）...

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Guys, read this article first and you will appreciate the difficulties in countering stealth. It's a much bigger problem that you may think.



Counters to Stealth

Because stealth is so important to current air
operations and military strategy, it is reasonable
to ask if and when it might be effectively
countered. Historians contend that every military
invention in history has been countered by new
inventions or tactics, in due time. The radar game
illustrates this principle, too. Radar changed the
survivability duel during the Battle of Britain in
1940. Stealth changed it back fifty years later, in
the Persian Gulf War of 1991. The most relevant
question to ask is not “can stealth be countered?”
but “how difficult is it to counter stealth with
known technology?”

The radar range equation that demonstrates how
lower RCS reduces the range of detection contains
several variables. To counter stealth with a monostatic
radar, the air defense radar would have to
greatly increase its gain at the receiver. The way to
do this would be to greatly increase the power of
the system. If the target aircraft had an RCS reduction
of 1,000 the radar power would have to
increase by a factor of 1,000 to detect it at the same
range as a non-stealthy aircraft. However, increasing
power is easier at long wavelengths, not at the
short, rapid frequencies commonly used for fire
control. Ultra-wide band radar poses a similar
problem. An ultra-wide band pulse could emit
waves at several different frequencies hoping to
catch the stealth aircraft at a weak point in its
RCS reduction. But transmitting over a wide band
diminishes the power in each band, cutting the
efficiency of the radar.

The second issue in discussions of counter-stealth
is that stealth aircraft are designed against monostatic
radars, the type used in nearly all military systems.
Monostatic radar couples the transmitter and
receiver at the same place, a process that simplifies
the crucial function of distance tracking. In theory,
a bistatic radar that placed the transmitter in one
location and the receiver in another might be able
to pick up what might be called the “trailing” RCS
that is directed away from the monostatic radar.
However, “bistatic radars, while simple in concept,
have many fundamental technical and operational
issues to overcome,” according to John
Shaeffer, radar cross section engineer at Marietta
Scientific in Georgia. The receiver antenna beam
must intercept its companion transmit beam, and
follow the transmit pulse which is moving at the
speed of light. Unless the transmitter and receiver
pulses are synchronized, distance measurement is
impossible. Even a workable bistatic radar must
then address the problem of how much volume of
airspace it can scan at a given power setting in a
given time. When the receiver, transmitter and target
are located on a straight line, the receiver can be
overwhelmed by the transmitter pulse, which hides
the target’s radar return. As Shaeffer put it, “this is
similar to looking into the sun for light scattered
from Venus.”1

The RCS reduction of stealth aircraft is difficult
to counter. Improvements in radar must go a very
long way to match the performance they were
designed to achieve against non-stealthy aircraft.
Concerns about countering stealth should pale in
comparison to those about the known and increasing
threats to conventional aircraft. The day will
probably come when reusable hypersonic military
spaceplanes replace jets as the primary vehicles
for ensuring aerospace dominance. Until then,
for as long as jet aircraft offer the most reliable
option for air superiority and air attack, stealth
will be indispensable.

F-22
The F-22 will also have the distinction of being
the first stealth aircraft capable of operating during
the day. Of all the possible “counters” to stealth,
perhaps the one that poses the greatest threat to
aircraft survivability is the trade-off in speed and
performance. The F-22 restores the aerodynamic
advantages of an air superiority fighter, while delivering
the penetration and bomb-dropping capabilities
of the F-117. The combination of these abilities
will position the F-22 to become the backbone of
air-to-air and air-to-ground operations ranging from
first-night attack in major theater wars to air defense.