Russian Radar systems

Gomig-21 wrote:So essentially, resonance means longer wavelengths that are a meter long and by being that long, they tend to overwhelm the subject they're bouncing off and that subject's stealthy attributes can only cope with such long wavelengths that scattering it or redirecting it by shaping or absorbing it via its RAM for only so much until an actual and identifiable return does come back which is discernable?  Am I getting it right in an even more super dumbed down version, or not?

kvs wrote:Even though 1 meter radar cannot scatter useful information from a 1 cm object like micrometer band waves, it will still scatter something since we
are dealing with photons and quantum mechanics.    One could scan a 1 cm object with a 1 m wavelength beam if the angles and intensity could
be varied.   Having more than one source of the scanning beam also helps a lot.   This way you get additional information that can be used to
construct an image of the target.   This assumes no resonance in the target.

But this is usually not practical under rapidly changing conditions such as movement of the target and the resources that can be deployed
to engage in this process are limited.   Resonance radars are nifty because there will be harmonics induced by a 1 m wavelength beam
that are of shorter and longer wavelengths.   In fact, they do not depend on the radar scanning beam details too much as long as we
are not talking much longer incoming wavelengths which rapidly weakens the amplitude of resonance harmonics and thus makes them
harder to detect.    So the job of resonance radars is to detect wavelengths expected to be generated in aircraft like objects.  

Modern radars really do undermine the effectiveness of stealth.   The monochrome radars of the 1950s are ancient history.

Gomig-21 wrote:

kvs wrote:Even though 1 meter radar cannot scatter useful information from a 1 cm object like micrometer band waves, it will still scatter something since we
are dealing with photons and quantum mechanics.    One could scan a 1 cm object with a 1 m wavelength beam if the angles and intensity could
be varied.   Having more than one source of the scanning beam also helps a lot.   This way you get additional information that can be used to
construct an image of the target.   This assumes no resonance in the target.

But this is usually not practical under rapidly changing conditions such as movement of the target and the resources that can be deployed
to engage in this process are limited.   Resonance radars are nifty because there will be harmonics induced by a 1 m wavelength beam
that are of shorter and longer wavelengths.   In fact, they do not depend on the radar scanning beam details too much as long as we
are not talking much longer incoming wavelengths which rapidly weakens the amplitude of resonance harmonics and thus makes them
harder to detect.    So the job of resonance radars is to detect wavelengths expected to be generated in aircraft like objects.  

Modern radars really do undermine the effectiveness of stealth.   The monochrome radars of the 1950s are ancient history.

 

So what you're basically saying is that Resonance radars send long, 1 meter wavelengths that also (by default?) create/induce harmonics within those wave lengths once they're bouncing off the target, and those harmonics create varied RETURN waves that are long and short which give more information on the target instead of returning only longer wavelengths since those really don't contain much detail by themselves.  Does that pretty much summarize it correctly in a really layman way, or is it an incorrect deduction of your post?

kvs wrote:Just as materials can resonate at certain vibrational frequencies (e.g. Tacoma Narrows bridge incident), they can also vibrate in the
EM realm as well.   All materials absorb since there are no perfect reflectors (and absorbers outside of black holes if they exist).   One
meter radar EM waves will go through materials including metal.   The Faraday cage effect from electrostatics applies to some extent
but since scanning waves are not some steady state illumination and include a magnetic component they will penetrate the skin of the aircraft
(with attenuation due to absorption and scatter).   Even the skin of the aircraft is a source of resonance harmonics and it does not have to
be just the frame, the engines or other "volume filling" objects.  

So think of the targeted aircraft as absorbing the 1 meter radar waves and then emitting a broad spectrum of waves with both shorter
and longer wavelengths compared to the scanning radar beam.  Being resonance harmonics, they do not form a continuous spectrum
of emissions but are organized in spikes depending on the characteristics of the aircraft.   So different aircraft will give different spectra
of resonance emissions but likely not wildly different.    So the return signal that the radar system needs to process is not 1 meter original
wavelength scanning beam scatter, but new wavelengths likely to form from resonance in the aircraft body.   This requires testing
with targets to figure out what bands to detect for resonance return signal.  

A detail that should be mentioned is that the amplitude of the scanning beam can be cranked up to produce a better return signal.
No amount of RAM coating will save you from this.   And no RAM coating works 100%.   In fact, since RAM is an absorber it must be
an emitter (in some other wavelengths).   So the aircraft will still be exposed to EM waves induced by the original radar scanning beam
and will produce harmonics in some other bands compared to what the radar beam itself would directly induce.    Regardless, cranking
up the scanning beam amplitude returns a "cornucopia" of resonance EM emissions that one could detect if one looked for them.

By contrast, using passive IR emissions does not allow you do dial the return signal since the source of those IR emissions is independent
of the radar (no longer radar really) system.   Also, IR is scattered and blocked by clouds and fogs more effectively than radar and
at least some of the resonance harmonics.

GarryB wrote:If you watch the combat approved series of videos there was one particular episode where there were a whole lot of different scale models shown of different aircraft and missiles and things and they were raised up by a cable system to be held up in the air with various radar and equipment around the place. The cable they were suspended from allowed the models to be rotated in various axis  so you could scan it with a radar and rotate it in real time to view the model with the radar from every possible direction.

This sort of thing creates a radar image in that frequency from that radar antenna for that target type... and they could do the same in optical and IR so they can store a 3D database of what objects look like in HF radar and IIR frequencies and use computer processing power to match this library of images from every potential angle with radar returns in the real world to rapidly identify a target and label it correctly within the system.

The Americans did something similar to develop stealthy designs... they just made shapes they guessed would work best... made models and hung them up in front of real radars and tested the results. Eventually thanks to a paper by a Soviet scientist they were able to create a mathematical model of how radar waves work in the real world and were then able to use computers to test thousands of shapes at a time and pick perhaps the best 5 or 10 to make and test in their testing facilities.

If they did what the Russians are doing now they likely would have realised the Iranian F-14 diving at them in Iranian waters in the 80s was actually a climbing Airbus... but if they can't tell something is climbing and then levelling off, and are convinced it was diving and accelerating... then no amount of computer help would matter I guess.

Hole wrote:
New radars

Gomig-21 wrote:This is really something else.  So I see the obvious 2 systems in Algeria and Egypt and the one(s) in Russia, but any idea what the 4 are that seem to be coming out of Iran?

LMFS wrote:

Gomig-21 wrote:This is really something else.  So I see the obvious 2 systems in Algeria and Egypt and the one(s) in Russia, but any idea what the 4 are that seem to be coming out of Iran?

Iranian OTH radars

kvs wrote:The testing of potential targets for resonance radar systems is necessary but not the end of the story.    With modern computing
power combined with wide spectrum detection it is possible to have real time adaptive detection.   Since the target will emit EM
in some form regardless, any new signals (not part of natural emissions) on the horizon can be "tuned" and followed.   The key
is the ability of the detection arrays, especially the phase-array components, to catch new signals.  

In some ways it is easier to cover more of the EM spectrum than to have models built on tests only.   The tests are useful for
giving information about generic resonant emissions of various structures.   So that helps to focus on certain regions of the
EM spectrum and devote more detection resources to them.  

Any flying object will be producing emissions that are not part of the normal atmospheric and ground emissions.  But these
signals may be weak enough to be missed if the focus of the radar system is too narrow.   The 1950s radars are the definition
of narrow focus since they detected the backscatter of the scanning beam.   This made stealth worthwhile.   In the 1960s
and against 3rd world countries that later.    But physics gives solutions to defeat stealth and it is a matter of development
and investment to achieve this.

Gomig-21 wrote:

LMFS wrote:

Gomig-21 wrote:This is really something else.  So I see the obvious 2 systems in Algeria and Egypt and the one(s) in Russia, but any idea what the 4 are that seem to be coming out of Iran?

Iranian OTH radars

I figured they were OTH radars since they have the same coverage as the Resonance-NE in Algeria and Egypt, but was wondering if they were a Russian type or they're domestic-built Iranian radars?

Over the horizon is really not that far when you think about the minimum distance is only 5 km until you start getting beyond the horizon, and these radars have a range of 600-1100km which are way beyond that distance which would be almost any type of radar.  Unless OTH means something else!?

Gomig-21 wrote:I figured they were OTH radars since they have the same coverage as the Resonance-NE in Algeria and Egypt, but was wondering if they were a Russian type or they're domestic-built Iranian radars?

Over the horizon is really not that far when you think about the minimum distance is only 5 km until you start getting beyond the horizon, and these radars have a range of 600-1100km which are way beyond that distance which would be almost any type of radar.  Unless OTH means something else!?

Hole wrote:A radar is not a weapon, there were no sanctions against selling them.

Hole wrote:A radar is not a weapon, there were no sanctions against selling them.

Isos wrote:

I think they are iranian copies of Rezonance. Probably done with russian help.

Radar horizon is not the same as visual horizon. For very low flying (100m) it's around 40km. For a target flying at 1km in aktitude it will be more like 100km... it varies with target altitude and radar mast height.

OTH use the atmosphere to bounce the radar signal so that it can see in those dead zones.



You can calculate radar horizon on this website :

http://members.home.nl/7seas/radcalc.htm