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> The problem is that it's likely the first realization you'll have a stealth aircraft is around is when it launches a missile at you. Stealth aircraft still r

by pps43 10y ago

> The problem is that it's likely the first realization you'll have a stealth aircraft is around is when it launches a missile at you. Stealth aircraft still reflect radiowaves, they just don't reflect them back at the source. This can be effectively countered by separating radar transmitter and receiver in space. It is also possible to use existing transmitters (e.g., FM radio, cell towers) to build passive radar that does not emit anything itself.

Recurecur 10y ago
"Stealth aircraft still reflect radiowaves, they just don't reflect them back at the source. This can be effectively countered by separating radar transmitter and receiver in space." There are also radar absorbing materials and coatings involved, though to be sure they don't absorb everything. The modern curved stealth airframes also diffuse the return, weakening it considerably. "It is also possible to use existing transmitters (e.g., FM radio, cell towers) to build passive radar that does not emit anything itself." Sure, although stealth aircraft are most vulnerable to long wavelength radar, which lack precise positional detection. Also, if you're using cell/FM etc. transmitters, those are easily shut down by strikes on power stations, or EMP. An interesting, revolutionary approach is quantum radar, which uses entanglement to detect photon interaction with the target. It's pretty far from prime time though. http://www.popsci.com/china-says-it-has-quantum-radar-what-does-that-mean http://www.popsci.com/china-says-it-has-quantum-radar-what-d...
- pps43 10y ago
  Diffusing the return is actually good for the radar. If all return goes in one direction and there happens to be no radar receivers in that direction, radar won't detect anything. With diffused return at least some of it is reaching the receivers. Cell tower signals have higher frequency than VHF, which makes position estimation easier. Cell towers will work for a few days even if power grid goes down. There are too many of them to take out individually. Nuclear blast has EMP powerful enough to burn them, but by that time you probably no longer need stealth. With access to baseband code in modern cell phones it might be possible to build distributed passive radar surreptitiously. There is enough processing power, exact time and location from GPS, and communication over LTE.

by pps43 10y ago

Recurecur 10y ago

"Stealth aircraft still reflect radiowaves, they just don't reflect them back at the source. This can be effectively countered by separating radar transmitter and receiver in space." There are also radar absorbing materials and coatings involved, though to be sure they don't absorb everything. The modern curved stealth airframes also diffuse the return, weakening it considerably. "It is also possible to use existing transmitters (e.g., FM radio, cell towers) to build passive radar that does not emit anything itself." Sure, although stealth aircraft are most vulnerable to long wavelength radar, which lack precise positional detection. Also, if you're using cell/FM etc. transmitters, those are easily shut down by strikes on power stations, or EMP. An interesting, revolutionary approach is quantum radar, which uses entanglement to detect photon interaction with the target. It's pretty far from prime time though. http://www.popsci.com/china-says-it-has-quantum-radar-what-does-that-mean http://www.popsci.com/china-says-it-has-quantum-radar-what-d...

pps43 10y ago
Diffusing the return is actually good for the radar. If all return goes in one direction and there happens to be no radar receivers in that direction, radar won't detect anything. With diffused return at least some of it is reaching the receivers. Cell tower signals have higher frequency than VHF, which makes position estimation easier. Cell towers will work for a few days even if power grid goes down. There are too many of them to take out individually. Nuclear blast has EMP powerful enough to burn them, but by that time you probably no longer need stealth. With access to baseband code in modern cell phones it might be possible to build distributed passive radar surreptitiously. There is enough processing power, exact time and location from GPS, and communication over LTE.