F-35 meets J-20 over South China Sea

[Song Hong]

Not interested in text book information. Am interested in practical application, specifically, usage against a low radar observable body. While it is technically true that you can install any antenna array of any dimension you want, that would be contrary to practical applications because an aircraft have limited volume everywhere. That is why the X-band is the common freq band for most applications.

You have one more chance before I expose your ignorance.

If you do not understand electro magnatics, then you fall into various conspiracy theory or people bs you believe. No way for you to have meta cognitation.


Engineering is about trade off.

 

[gambit]

If you do not understand electro magnatics, then you fall into various conspiracy theory or people bs you believe. No way for you to have meta cognitation.


Engineering is about trade off.

While what you said was technically correct, that we can install any freq into an airborne platform, supposedly using a long wavelength to detect a low radar observable body, even at poor target resolutions, it is at least problematic if not outright impractical.

There is an inverse relationship between antenna dimension and operating freq affecting beamwidth, meaning, for any operating freq, the smaller the array, the wider the beamwidth, conversely, the larger the array, the smaller the beamwidth. And we want smaller beamwidth.

Here is the problem with beamwidths...

There is something called 'resolution cell'...

Definition: radar resolution cell

radar resolution cell: The volume of space that is occupied by a radar pulse and that is determined by the pulse duration and the horizontal and vertical beamwidths of the transmitting radar. Note: The radar cannot distinguish between two separate objects that lie within the same resolution cell.​

​

The highlighted last sentence is important. If multiple bodies are inside one cell, the radar will resolve to one body. That is NOT what we want but the problem is that we do not know if there are multiple bodies in the first place.

So if we fly with HF or VHF or UHF freqs, the beamwidths would be so wide that it would pick up just about everything in the sky and EVERYTHING the beam picked up would be displayed as one huge blob on the scope.

 

[Song Hong]

While what you said was technically correct, that we can install any freq into an airborne platform, supposedly using a long wavelength to detect a low radar observable body, even at poor target resolutions, it is at least problematic if not outright impractical.

There is an inverse relationship between antenna dimension and operating freq affecting beamwidth, meaning, for any operating freq, the smaller the array, the wider the beamwidth, conversely, the larger the array, the smaller the beamwidth. And we want smaller beamwidth.

Here is the problem with beamwidths...

There is something called 'resolution cell'...

Definition: radar resolution cell

radar resolution cell: The volume of space that is occupied by a radar pulse and that is determined by the pulse duration and the horizontal and vertical beamwidths of the transmitting radar. Note: The radar cannot distinguish between two separate objects that lie within the same resolution cell.​

​

The highlighted last sentence is important. If multiple bodies are inside one cell, the radar will resolve to one body. That is NOT what we want but the problem is that we do not know if there are multiple bodies in the first place.

So if we fly with HF or VHF or UHF freqs, the beamwidths would be so wide that it would pick up just about everything in the sky and EVERYTHING the beam picked up would be displayed as one huge blob on the scope.

The VHF has problem of resolution. I always highlighted that.

If you know DSP. you know there is many solution on this issue. I give one suggestion.

One can fly multiple plane with VHF radar. Base on the simultaneous synchronuzed collection of images at different position, one perform triangulation. Then resolution will improve.

When VHF see the stealth fighter the AWAC will stay far away. Then groups of J20 will engage the stealth fighters.

YOu are talking to an electronic warfare engineer.

 

[gambit]

The VHF has problem of resolution. I always highlighted that.

But you did not know of the resolution cell and beamwidth. You can try to process that blob all you want, but if you are under physical and time constraint, you will still have just a large EM blob.

If you know DSP. you know there is many solution on this issue. I give one suggestion.

One can fly multiple plane with VHF radar. Base on the simultaneous synchronuzed collection of images at different position, one perform triangulation. Then resolution will improve.

When VHF see the stealth fighter the AWAC will stay far away. Then groups of J20 will engage the stealth fighters.

Which leads back to what I said earlier about having a physical and data processing complex system. It makes your system less flexible in maneuverability, prefers the target to be in ideal spatial locations, and let everyone know you are flying transmitters all over the airspace. What you do not know is that being low radar observable does not give the pilot licence to ignore the EM threats and the US have forty yrs of testing and refining our methods. No one come close, not even China.

YOu are talking to an electronic warfare engineer.

Sure.

In the final analysis, the TACTICAL COMBAT advantage remains with the 'stealth' platform.

 

[HuangHe]

General Wilsbach said that E3 is too old and couldn't see J20 coming.

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[Daniel808]

Poor F-35 Detected by Chinese Anti-Stealth Radar, and China send J-20 Stealth Fighter to Intercept to give the message.


What an Embarassing moment for US

 

[Song Hong]

But you did not know of the resolution cell and beamwidth. You can try to process that blob all you want, but if you are under physical and time constraint, you will still have just a large EM blob.


Which leads back to what I said earlier about having a physical and data processing complex system. It makes your system less flexible in maneuverability, prefers the target to be in ideal spatial locations, and let everyone know you are flying transmitters all over the airspace. What you do not know is that being low radar observable does not give the pilot licence to ignore the EM threats and the US have forty yrs of testing and refining our methods. No one come close, not even China.


Sure.

In the final analysis, the TACTICAL COMBAT advantage remains with the 'stealth' platform.

The backend processing is a problem. You need an AWAC very close due to high baseband datarate throughput of radar signal. But it is a risk itself as OPFOS stealth fighters target AWAC.

There is still solution. One is to use another stealth fight as onboard EW plane and supercomputer. J-20S fits the mission.

Modern AWACs such as KJ500 and E3 can see stealth fight at more than 100km. This is beyond the range of AIM 120. The J20 groups quickly move forward and AWAC quick retreat.

This should be the strategy.

BTW China has deployed lots of land base HF radar along the sea. These landbase HF radars can detect stealth planes at several hundreds km. The KJ500 could "focus" on the area. It will greatly increase the detection range.

Another thing that complicates this problem is both China and US got EW planes. HF and VHF is easy jammable due to narrow bandwidth.

However once Chinese HF landbase HF radar detects abnormal radar signature at HF, they most likely triggers that OPFOS is around. They cannot pinpoint exact location. They will pintpoint an area.

 

[FuturePAF]

With the US producing approx. 100 F-35s for itself and its partners, China will have to step it up and produce at least 50 J-20s a year to keep up.