5 ms·
Using 60 GHz for communication at these distances is pretty strange because 60 GHz is strongly attenuated by the atmosphere. Not only that, but atmospheric atte
by gene-h 7y ago
Using 60 GHz for communication at these distances is pretty strange because 60 GHz is strongly attenuated by the atmosphere. Not only that, but atmospheric attenuation peaks at 60 GHz because that's what oxygen absorbs[0]. Some military satellites even use 60 GHz for intersatellite links because it's highly attenuated by the atmosphere, making eavesdropping more difficult
[0]https://en.wikipedia.org/wiki/Extremely_high_frequency#Propagation https://en.wikipedia.org/wiki/Extremely_high_frequency#Propa...
- danesparza 7y agoAgreed. 60GHz appears to be allocated for fixed inter-satellite communications (probably for this reason): https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf
- peter_d_sherman 7y agoI read some of the above PDF... what's amazing to me is that a whole bunch of names of foreign countries pop-up over and over again in this document, specifically with assigned frequency ranges, as if the FCC is regulating frequency ranges in foreign countries... Before reading this, it seemed self-evident (to me) that the FCC's regulatory power does not extend to those foreign countries... Although, perhaps the FCC's regulatory powers do in fact extend to those countries via international agreements and/or treaties? Does someone know? How does that work?
- tssva 7y agoIf you re-read the document you will see that there is a note regarding the international frequency ranges indicating that they are taken from the 2016 edition of the ITU Radio Regulations.
- peter_d_sherman 7y agoInteresting! So ITU is sort of the international standards organization for radio frequency bands... makes sense!
- jjoonathan 7y agoThe next generation of RF communications always clusters around RF spectrum that the previous generation considered undesirable. From shortwave radio to 2.4 GHz, this has always been the case. It's not a huge stretch to suspect that it might be the case for 60 GHz as well.
- blackguardx 7y agoYeah, this is also why 60 GHz FCC power limits are higher because they don't expect you will interfere with anyone. I thought it was usually thought of as an "in room" transmission medium.
- magicsmoke 7y agoThe high attenuation at 60 GHz is actually an advantage since it lets you put lots of highly directional antennas in close proximity while attenuating their side lobes to lower interference. If your attenuation is 20 dB/km but you have a 22 dBi gain antenna, a 1.5 km range seems pretty feasible.