I've never heard of a conductor called an "absorber" instead...anyways, the proper use of the word absorber in this case referring to EM, is usually referred to as electrical absorbers for specific frequencies. Since we weren't talking about radar absorbent paint or composites but about oxide coated canopies, your use of the term "absorber" is inappropriate. The conductive canopy oxide coating is applied via deposition and makes EM behave similarly to how EM travels along the rest of the surface of a treated stealth airframe. The difference in shaping of the canopy are under the same stealth shaping rules as is used on the rest of the respective airframe. That's why the F-117A canopy has saw tooth edges for its shaping and the J-20 bubble canopy for its shaping doesn't.
Really? Inappropriate? Then I suggest you contact the world's aviation authorities, specifically those in radar engineering to tell them that.
A sponge is an absorber and a conductor. You made the typical mistake of a scientifically ignorant who confused the application with the property (or behavior). A sponge cannot absorb liquids unless one of properties (or behaviors) is that of being conductive somehow to liquids. You confused one of the contexts of 'absorb', which is to draw in, to be a distinct behavior when the behavior is typical -- conduction.
A standard canopy is a pass-through material, which is another behavior made possible by conductivity, or little or no resistance. The result is that radar signals entered the cockpit well and with alternating destructive and constructive interferences, the cockpit become an EM resonating beacon. A treated canopy with an absorber or conductor film will not allow conductivity in one direction -- pass-through -- but conductivity on another direction -- surface traveling waves. Whether is is pass-through or surface waves, both are not possible unless there is conductivity. The issue is which direction do we want.
So what I said is contextually and technically correct, that an absorber is or rather
MUST BE a conductor and a conductor can be exploited in application to be an absorber.
Further...If my usage of 'absorber' is inappropriate, then those saw-tooth patterns we see cannot be called 'geometric absorber' because that is how they are called in the industry...
Convoluted (APC) | www.siepel.com
APC are historically the first absorbers using geometrical transition principles. Their excellent performances and characteristics above 10 GHz for minimized dimensions make them ideal for most applications in this range of frequencies.
The word 'transition' here mean changes. In other words, physical geometries are exploited to
DENY a receiver of signals. In RCS control techniques, anything that can be used to deny a receiver of signals is called an 'absorber'.
Where there are surface waves, if the waves encounter a different material that has electrical loading or magnetic conductive properties, that material can be called an 'electrical absorber', or some would call it a 'passive cancellation' technique.
IEEE Xplore - Reduction of the radar cross section of a moderate cylindrical structure using central impedance loading
A theoretical study on the minimization of the radar cross section (RCS) of a cylindrical structure of moderate radius centrally loaded by a lumped impedance that is illuminated by a plane electromagnetic wave at normal broadside incidence is presented. Expressions for the induced current on the surface of the cylinder and for the RCS are obtained, and an equation for the optimum loading impedance that minimizes the RCS for moderate cylinders is also derived. The reduction of the RCS is achieved because the impedance that centrally loads the cylinder reduces the superficial current and consequently the RCS. The current and impedance equations are derived using the Hallen' method for calculating the current distribution in antennas. Computed curves of the induced current distribution in the cylinder and of the RCS are presented and experimental results for moderate impedance loading of dipoles not much longer than λ/2 are compared with the theoretical computations. For such dipoles, the broadside RCS can be reduced by 30 to 40 dB with appropriate passive center loading.
Notice the mention of a cylinder. Why a cylinder but not a plate? Because electrical absorber or passive cancellation works best against surface waves. This lead to the next debunking of your argument.
That's the strong impression I get because you constantly butt into every conversation concerning stealth and invariably end up talking about traveling waves in one way or another while giving comparatively rare mention of specular reflections. Martian2 and you once had a debate about "continuous curvature" and he had a strong point about with an example about a cylinder and its unnecessarily large potential radar return, along the straight edge view from the straight on specular return from an illuminating radar, due to its lack of "continuous curvature" and you kept harping about traveling waves while completely ignoring his point about the specular reflections.
The phrasing 'continuous curvature' is something he made up. He is also grossly wrong about the cylinder because the source he brought on does not mention the 10 lambda rule, which comes into play whenever a radar signal encounters a curvature on a sphere or a cylinder. A cylinder does not have an 'edge on' perspective but an 'end on' perspective. At this point, we would be dealing with a plate.
It is funny that if he enter a thread with his proven nonsense it is 'informative' and the Chinese boys would be tripping over themselves thanking him for the 'useful' posts but if I enter the same to debunk him it is 'butting' in.
But if his nonsense is educational and 'useful' to the Chinese boys here, we have nothing to fear about of that supposedly 'high Chinese IQ' they so often boast about.
That's what is called willful ignorance and/or purposeful deception. Either that, or you actually do believe specular reflections and shaping take a back seat since you gave it zero importance. That's par for the course in every single one of your debates since your obviously not here to actually debate anything.
The one who continues to exhibit either willful ignorance or intellectual dishonesty here is still
YOU, friend.
I will sum it up again...
- If the focus is on a mono-static attack, then specular reflections are dominant in signal processing, meaning the only thing to worry about is how to handle specular reflections.
- If the focus is on
BOTH mono- and bi-static attacks, then
BOTH specular and surface waves are dominant whenever they occur.
Incorrect:
- (Specular) or (surface waves). This is your interpretation of my position.
Correct:
- (Specular) or (specular and surface waves). This is my true position.
Get it now, liar?
I will now put it into real world examples, see if you can grasp it...
If the only thing we want to act against, as in denial of reflected signals, is a mono-static attack, then angled faceting technique is what we will use, and we have with the F-117. On the opposite side of the radar, diffracted signals are free to radiate anyhow they want. We do not care. As long as the direction of the seeking radar is relatively clean of reflected/diffracted signals, we are 'stealthy'.
But if we worry about the possibility that an adversary might deploy a bi-static radar against us, and since the angled faceting technique offers limited diffraction controls due to aerodynamic demands, why not introduce curvatures to
INDUCE surface wave behaviors? The surface expanse of each curve and the degree of arc give us greater 'electrical paths' upon which those surface waves must travel and as they travel, the energy they bleed off via 'leaky waves' can be below a certain threshold.
IEEE Xplore - Propagation properties of longitudinal leaky surface waves on lithium tetraborate
Theoretical and experimental results of longitudinal leaky surface waves with a higher phase velocity than that of ordinary leaky surface waves and a low propagation loss on lithium tetraborate (LBO) are investigated in detail.
The result of all this theorizing and experimentation are the B-2, F-22, and F-35, which look radically different from the F-117 but all are quite equally 'stealthy' to the original attempt of 'stealth', the F-117.
This is the third time that I have explained to you the differences between the mono-static and bi-static configurations and why certain behaviors are prominent at which point. I cannot dumb it down further. I am not well versed in 'Chinese physics'. So looks like it is
YOU who are par for the stupidity course.
I suggest you tone down accusations for things that are simply not true. I have never disregarded the importance of all-aspect stealth and have had conversations with you and others stretching back years about various ways to improve stealth detection regarding multi-modal radars involving various radar bands, greater computing power, different filters, cell tower style radar grids, SAR radar grids, UAV radar grids, RWR radar grids, etc, etc. Your needless anecdotes concerning why the F-117A is retired is the reason why traveling waves is even a concern today. But, it is still secondary.
No, it is not secondary. At least not to US. But I sincerely do hope that the Chinese engineers do take your position. It will make shooting down Chinese not-so-stealthy fighters that much easier.
That's fine, if your intention is to actually debate. However, if you choose to ignore one while concentrating on the other or vice-versa depending on whatever you are "debating" about, then there is a problem. It doesn't help that you consistently nitpick grammar and use it as part of your debates. lol The word disingenuous is used a lot nowadays.
Calling for proper contexts is not nitpicking on grammar, which is about sentence structure.
Take the word 'composite', for example. Many here bandied that word around casually when it comes to 'stealth'. For those of us who have relevant experience, which I can see you and the Chinese boys do not have, the word 'composite' in aviation have more to do with weight saving measures than with RCS controls. Plywood and concrete are composites. Even steel is a composite.
Civil - Emerging Construction Technologies
MMFX Steels proprietary chemical composition and production process control the steels martensitic microcomposite...
Plywood and concrete are 'gross constituents' composites. Steel is a microstructural composite. See if you can look up 'elemental composite' where the majority of materials are made up of many different atoms.
So no, I am not nitpicking but correcting misconceptions.
If that's your attitude then why even waste time debating the unknown? Isn't it a waste of time then because it sure seems like you have alot of time to be writing up what looks like 40 pages per day of what you consider useless messages in these debates about phantom projects and items.
The more important question is why are the Chinese boys wasting their time speculating on that same unknown? But if you deem it valuable that they speculate, then it is odd that debunking their nonsense is a waste of time.
I never said the Russians cannot. I have a lot of respect for Russian engineers given their relatively limited resources and I'm sure they will eventually make changes to the canopy to address this weakness. How you can claim a traditional canopy is a minor stealth issue is surprising given that RCS is now measured in the fractions of a sq/m2.
Wow...See post 228 =>
http://www.defence.pk/forums/chinese-defence/158465-report-indian-mmrca-chinese-16.html#post2603607