Zhuhai Airshow 2022


SEAD

Junior Member
Registered Member
No…usual publicly reported stealth figures are in X-band.
“The patent claims composites with CNT-infused fibers are capable of absorbing EM waves from 0.1 MHz to 60 GHz, a bandwidth unheard of in commercial absorbers, with particular effectiveness in L- through K-band. The patent does not quantify the absorptivity, but does say the panels would be “nearly a black body across . . . various radar bands.”

From aviationweek
 

latenlazy

Brigadier
“The patent claims composites with CNT-infused fibers are capable of absorbing EM waves from 0.1 MHz to 60 GHz, a bandwidth unheard of in commercial absorbers, with particular effectiveness in L- through K-band. The patent does not quantify the absorptivity, but does say the panels would be “nearly a black body across . . . various radar bands.”

From aviationweek
1) Do we know is this “patent” is actually used on the F-35, or whether that’s just speculative?
2) Do we know the amount of absorption at longer wavelengths is the same as on shorter wavelengths?

If you can’t answer those questions then we simply don’t have enough information to conclude anything about the claim you’re sharing.
 

SEAD

Junior Member
Registered Member
1) Do we know is this “patent” is actually used on the F-35, or whether that’s just speculative?
“Tom Burbage, then executive vice president for the F-35 program,disclosed the incorporation of “fiber mat” technology, describing it as the “biggest technical breakthrough we’ve had on this program.”

from the same aviationweek report.
2) Do we know the amount of absorption at longer wavelengths is the same as on shorter wavelengths?
“The same as” is physically impossible, but effective is very possible.
 

latenlazy

Brigadier
“Tom Burbage, then executive vice president for the F-35 program,disclosed the incorporation of “fiber mat” technology, describing it as the “biggest technical breakthrough we’ve had on this program.”

“The same as” is physically impossible, but effective is very possible.
If you don’t know for a fact that the -30 dbsm reduction applies to longer wavelengths there really is no basis for the claim that this ram gets -30 dbsm at longer bands.

(And if I misunderstood your comment, and you just mean the F-35 has -30 dbsm material for shorter bands, that’s not exactly special. We’ve seen materials exhibited in this year’s and last year’s Zhuhai with as much as -40 dbsm for certain bands).
 

SEAD

Junior Member
Registered Member
If you don’t know for a fact that the -30 dbsm reduction applies to longer wavelengths there really is no basis for the claim that this ram gets -30 dbsm at longer bands.

(And if I misunderstood your comment, and you just mean the F-35 has -30 dbsm material for shorter bands, that’s not exactly special. We’ve seen materials exhibited in this year’s and last year’s Zhuhai with as much as -40 dbsm for certain bands).
Although I forgot where the -30 was from, “with particular effectiveness in L-“ would be a good footnote.
 

taxiya

Brigadier
Registered Member
I’m sure those reports about F35 were talking about UHF band (although I don’t fully believe them).
Where did you get that (UHF band)? Care to show us those reports?

This band (400M-2G) is not necessarily such big antenna except in its low end, in fact cellphones also work here.
You apparently do not know what you are talking about by the bold texts.

Meter wave module is huge compared to X-band module exactly related to wave length, like more than 10 times in size. Same number of module means the whole panel is more than 10 times in size. So yes very thing working in this band has to be huge compared to X-band counterpart.

Cellphone towers work in detecting stealthy aircraft NOT due to its frequency/wave length. It is the blocking/disturbance that are caused by the aircraft when travelling through a grid of cell towers. That disturbance are detected because the cell tower signals are synced. The frequency plays no role.
 
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taxiya

Brigadier
Registered Member
“The patent claims composites with CNT-infused fibers are capable of absorbing EM waves from 0.1 MHz to 60 GHz, a bandwidth unheard of in commercial absorbers, with particular effectiveness in L- through K-band. The patent does not quantify the absorptivity, but does say the panels would be “nearly a black body across . . . various radar bands.”

From aviationweek
"nearly black body" is just a bloating phrase, black body is like infinite absorption. So how near is that "nearly"? -4db or -30db, or -1000db? Without quantification the paper means nothing.
Although I forgot where the -30 was from, “with particular effectiveness in L-“ would be a good footnote.
-4db is 61% reduction of power of the incoming signal, that can be particularly effective. As I said above, no quantification means nothing.
 
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SEAD

Junior Member
Registered Member
Where did you get that (UHF band)? Care to show us those reports?
L band is in UHF(or beside it, depends on which definition you’re using), plz.
-4db is 61% reduction of power of the incoming signal, that can be particularly effective.
possibility of detection depends on ratio and that’s why we use logarithms, I don’t know why you think “61%” is effective after all if you use linear scale an absorber used in anechoic chamber is “0.0001%” and a stealthy airplane can be “0.001%”.
You apparently do not know what you are talking about by the bold texts.
In fact I was a RF engineer, anyway, if you believe you’re personification of truth, trust yourself.
 
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latenlazy

Brigadier
Although I forgot where the -30 was from, “with particular effectiveness in L-“ would be a good footnote.
“Particular effectiveness for L band” needs to be quantified and contextualized. What does “particular effectiveness” mean? Can’t just mash up contexts between one claim about -30 dbsm and another claim about “particular effectiveness in L” willy nilly…
 

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