5 ms·

> Then there's the millimeter wave stuff. [...] I think this is the part the FAA is objecting to for now. mmWave 5G signals are in the 24-54 GHz range (f = c /

> Then there's the millimeter wave stuff. [...] I think this is the part the FAA is objecting to for now. mmWave 5G signals are in the 24-54 GHz range (f = c / 0.001 m ≈ 30 GHz)

therein 5y ago
This makes me nervous. The O2 peak at 60GHz. What are your opinions on it? If we get that peak of attenuation at 60GHz, what's happening to that energy? The common wisdom would say it heats up but that's not guaranteed. https://i.imgur.com/KUR4XmX.png https://i.imgur.com/KUR4XmX.png https://i.imgur.com/iUD2v4D.png https://i.imgur.com/iUD2v4D.png https://www.5gamericas.org/wp-content/uploads/2020/12/InDesign-Understanding-mmWave-for-5G-Networks.pdf https://www.5gamericas.org/wp-content/uploads/2020/12/InDesi...
- lumost 5y ago
  What else would happen to the energy? It’ll turn into heat + some re-emissions.
  - jcims 5y ago
    Not to feed the trolls but here is one example: Tumor Treating Fields are an FDA-approved mechanism for treating certain cancers (mostly gliomas). The exact mechanism isn’t understood, but it seems that prolonged exposure to low power alternating electrical fields in the 100-500kHz region interferes with cell mitosis [1]. I haven’t read about it recently but at the time the speculation was that it was basically disrupting microtubule formation by physically agitating polar molecules involved with the process. The application from Optune and others uses contact electrodes to drive a small potential gradient though the skull and into the brain. We know radio frequency also affects polar molecules, mostly to heat up meals. Obviously at multi-GHz carrier frequencies we wouldn’t expect to see this behaivor emerge. However, most digital protocols don’t operate with continuous carriers..the break comms into frames and do things like frequency hopping at much lower periodicity than the carrier. If there was something dumping energy into the cytoplasm on a 2-10 microsecond interval, it could have similar effects. Do i think 5g is going to cure brain cancer? Probably not, but the body is ridiculously complex and can be surprising. I think we just have to find a way to be able to talk about these concerns fruitfully rather than just try to squash them, because that’s generally where the trouble seems to start. 1 - https://pubmed.ncbi.nlm.nih.gov/33080774/ https://pubmed.ncbi.nlm.nih.gov/33080774/
    - therein 5y ago
      Thank you. Pretty much the answer I wanted to give, but much better than I could. And I am not just trying to latch onto the first unknown that's brought up under my comment, these are very similar to the concerns that I had in mind and wanted to bring up. At the wavelengths we would now be dealing with and exposing ourselves to, there may be - and with some evidence already pointing there probably being surprising and not immediately intuitive (mostly) biological interactions or disruptions to interactions our biology relies on that we are yet unaware or haven't understood leading to phenomenons we haven't considered such as the example you've given.
      - jcims 5y ago
        I tend to be a bit of a fence rider when it comes to these types of things. Re: 5g we have so much accumulated knowledge and experience dealing with RF that the likelihood that we're going to be caught completely offguard and have no reasonable mitigation seems pretty low. At the same time, it's pretty obvious that our biology didn't have an opportunity to adapt to the types of energy we're putting into the environment and we'd be well served to keep an open mind about what the possible effects could be and how we would test and/or monitor for them. There are other contemporary topics that suffer this same pathology. Reasonable questions raised in good faith get slapped down regularly and I think we pay a collective price for it. Of course some questions aren't reasonable and certainly not all are raised in good faith, so it's not exactly an easy problem to solve.
        monetus 5y ago
        I keep wondering if any insects are going to discombobulated by thinking along those lines - but am a complete layman
        jcims 5y ago
        Affected, absolutely. Unknown to what degree or if it would be any worse then the billions smashed on windshields or fogged out of existence every year. Interesting paper on using EM simulations on finely detailed insect models to determine net energy absorption and associated properties: https://www.nature.com/articles/s41598-018-22271-3 https://www.nature.com/articles/s41598-018-22271-3
- JaimeThompson 5y ago
  "The common wisdom would say it heats up but that's not guaranteed." If it does something other than turn into heat the laws of thermodynamics are wrong which is somewhat unlikely.
- jdiez17 5y ago
  Sure, 60 GHz may be a resonant frequency of O₂ molecules and signals at that frequency may transfer energy to them and thus heat them up. However, remember that radio signals lose energy to free space proportional to the (distance and frequency) _squared_ [1]. A 60GHz signal is attenuated by 88dB at 10 meters. That means that if it is transmitted with 100 W (20dBW), the RF power that arrives at your position is -68dBW, or 0.000158 milliwatts. That isn't going to heat up much. [1] https://en.wikipedia.org/wiki/Free-space_path_loss https://en.wikipedia.org/wiki/Free-space_path_loss
  - mlyle 5y ago
    Note that this math is misleading for calculating how much things will heat up, because effective antenna aperture of the thing that you'd heat up increases with the square of frequency. So the square terms of frequency cancel each other out. It's still small, but the best simple approximation is just to take the 100W and divide by the proportion of the antenna pattern your target occupies. A 100W source on 2GHz or 60GHz at 10 meters distance is going to dump about the same amount of energy into you. If the transmit antenna has 3dB of gain, that's going to be about 50mW.
    - jdiez17 5y ago
      That's interesting. I'm not quite sure how that works but I'll look into it. If you have some resources, I'd appreciate it!
      - mlyle 5y ago
        See the derivation section in your link. It's assuming an isotropic antenna at the receiver, whose effective area gets smaller as the frequency increases. But people do not get smaller as the frequency increases: they occupy the same fraction of the 10m radius sphere around the antenna.
- RF_Savage 5y ago
  The power levels are low to begin with, so heating up the air is hard to even measure, let alone notice. It's why 60GHz is license free and used for WiGig, wireless HDMI and short haul microwave links like the ones from Mikrotik. The heavy oxygen attenuation makes it commercially worthless. Same reason why there's a license free band on 24GHz too. 24GHz suffers from water vapor absorption and has heavier attenuation than adjecent bands thanks to that. For example Ubiquiti AirFiber uses license free 24GHz.
- NavinF 5y ago
  Stop spreading FUD. ~60ghz radar has been used by cars for for cruise control and parking for many years now at much higher power levels than what phones can transmit. Some phones have mmWave radar for gestures too. We’d use even higher frequencies if it wasn’t for the terahertz gap.
  - therein 5y ago
    Spreading FUD isn't my intention. If anything I am hoping to alleviate the FUD that open-mindedly reading these documents and plans induce in my mind. I appreciate and read the honest and detailed technical takes on the topic here. Especially acknowledging uncertainty and a healthy amount of doubt are pretty essential to the epistemological pursuit. And fear may arise when the uncertainty and doubt are not dispelled with reason.
- desine 5y ago
  There's also the issue that with 5G phased array antennae, tx power limits are not restricted as tightly. With a standard single tx antenna, it's easy to calculate the amount of EM energy it can create in the 3D space around the antenna. With phased array beamforming, you're using using multiple small antennae and amplifying the signal beyond the sum of the individual outputs. The safety ratings for EM radiation around phased arrays tend not to be calculated on the theoretical maximum TX power, but on the typical usage. The result is that with low enough level access to the firmware, someone could theoretically weaponize a 5G antenna to produce unsafe levels of RF energy, as well as aim the antenna without physically moving the hardware. This sounds far-fetched, and it is, but I wouldn't be surprised if we see it done in a lab, like some of the other practically infeasible but bleeding edge cool hacks.
  - jdiez17 5y ago
    > With phased array beamforming, you're using using multiple small antennae and amplifying the signal beyond the sum of the individual outputs. No, that's impossible. The RF power imparted onto the EM field by any antenna array is equal to or less than the sum of the output power of each antennae.
    - MereInterest 5y ago
      I think the argument is that while the total power over the full 4π is equal to the sum of the input power, the constructive/destructive interference cause there to be higher power output within some solid angle. But my understanding is that the limit are for avoiding interference from other devices, not for human safety, and that any reasonable amount of non-ionizing radiation is incredibly safe for humans. Congestion wouldn't be impacted by the beamforming, because on average any increase in intensity at one angle would be countered by a decrease at some other angle.
      - deleted 5y ago
        [deleted]
      - marcan_42 5y ago

> Then there's the millimeter wave stuff. [...] I think this is the part the FAA is objecting to for now. mmWave 5G signals are in the 24-54 GHz range (f = c / 0.001 m ≈ 30 GHz)

therein 5y ago

This makes me nervous. The O2 peak at 60GHz. What are your opinions on it? If we get that peak of attenuation at 60GHz, what's happening to that energy? The common wisdom would say it heats up but that's not guaranteed. https://i.imgur.com/KUR4XmX.png https://i.imgur.com/KUR4XmX.png https://i.imgur.com/iUD2v4D.png https://i.imgur.com/iUD2v4D.png https://www.5gamericas.org/wp-content/uploads/2020/12/InDesign-Understanding-mmWave-for-5G-Networks.pdf https://www.5gamericas.org/wp-content/uploads/2020/12/InDesi...

lumost 5y ago
What else would happen to the energy? It’ll turn into heat + some re-emissions.
- jcims 5y ago
  Not to feed the trolls but here is one example: Tumor Treating Fields are an FDA-approved mechanism for treating certain cancers (mostly gliomas). The exact mechanism isn’t understood, but it seems that prolonged exposure to low power alternating electrical fields in the 100-500kHz region interferes with cell mitosis [1]. I haven’t read about it recently but at the time the speculation was that it was basically disrupting microtubule formation by physically agitating polar molecules involved with the process. The application from Optune and others uses contact electrodes to drive a small potential gradient though the skull and into the brain. We know radio frequency also affects polar molecules, mostly to heat up meals. Obviously at multi-GHz carrier frequencies we wouldn’t expect to see this behaivor emerge. However, most digital protocols don’t operate with continuous carriers..the break comms into frames and do things like frequency hopping at much lower periodicity than the carrier. If there was something dumping energy into the cytoplasm on a 2-10 microsecond interval, it could have similar effects. Do i think 5g is going to cure brain cancer? Probably not, but the body is ridiculously complex and can be surprising. I think we just have to find a way to be able to talk about these concerns fruitfully rather than just try to squash them, because that’s generally where the trouble seems to start. 1 - https://pubmed.ncbi.nlm.nih.gov/33080774/ https://pubmed.ncbi.nlm.nih.gov/33080774/
  - therein 5y ago
    Thank you. Pretty much the answer I wanted to give, but much better than I could. And I am not just trying to latch onto the first unknown that's brought up under my comment, these are very similar to the concerns that I had in mind and wanted to bring up. At the wavelengths we would now be dealing with and exposing ourselves to, there may be - and with some evidence already pointing there probably being surprising and not immediately intuitive (mostly) biological interactions or disruptions to interactions our biology relies on that we are yet unaware or haven't understood leading to phenomenons we haven't considered such as the example you've given.
    - jcims 5y ago
      I tend to be a bit of a fence rider when it comes to these types of things. Re: 5g we have so much accumulated knowledge and experience dealing with RF that the likelihood that we're going to be caught completely offguard and have no reasonable mitigation seems pretty low. At the same time, it's pretty obvious that our biology didn't have an opportunity to adapt to the types of energy we're putting into the environment and we'd be well served to keep an open mind about what the possible effects could be and how we would test and/or monitor for them. There are other contemporary topics that suffer this same pathology. Reasonable questions raised in good faith get slapped down regularly and I think we pay a collective price for it. Of course some questions aren't reasonable and certainly not all are raised in good faith, so it's not exactly an easy problem to solve.
      - monetus 5y ago
        I keep wondering if any insects are going to discombobulated by thinking along those lines - but am a complete layman
        jcims 5y ago
        Affected, absolutely. Unknown to what degree or if it would be any worse then the billions smashed on windshields or fogged out of existence every year. Interesting paper on using EM simulations on finely detailed insect models to determine net energy absorption and associated properties: https://www.nature.com/articles/s41598-018-22271-3 https://www.nature.com/articles/s41598-018-22271-3
JaimeThompson 5y ago
"The common wisdom would say it heats up but that's not guaranteed." If it does something other than turn into heat the laws of thermodynamics are wrong which is somewhat unlikely.
jdiez17 5y ago
Sure, 60 GHz may be a resonant frequency of O₂ molecules and signals at that frequency may transfer energy to them and thus heat them up. However, remember that radio signals lose energy to free space proportional to the (distance and frequency) _squared_ [1]. A 60GHz signal is attenuated by 88dB at 10 meters. That means that if it is transmitted with 100 W (20dBW), the RF power that arrives at your position is -68dBW, or 0.000158 milliwatts. That isn't going to heat up much. [1] https://en.wikipedia.org/wiki/Free-space_path_loss https://en.wikipedia.org/wiki/Free-space_path_loss
- mlyle 5y ago
  Note that this math is misleading for calculating how much things will heat up, because effective antenna aperture of the thing that you'd heat up increases with the square of frequency. So the square terms of frequency cancel each other out. It's still small, but the best simple approximation is just to take the 100W and divide by the proportion of the antenna pattern your target occupies. A 100W source on 2GHz or 60GHz at 10 meters distance is going to dump about the same amount of energy into you. If the transmit antenna has 3dB of gain, that's going to be about 50mW.
  - jdiez17 5y ago
    That's interesting. I'm not quite sure how that works but I'll look into it. If you have some resources, I'd appreciate it!
    - mlyle 5y ago
      See the derivation section in your link. It's assuming an isotropic antenna at the receiver, whose effective area gets smaller as the frequency increases. But people do not get smaller as the frequency increases: they occupy the same fraction of the 10m radius sphere around the antenna.
RF_Savage 5y ago
The power levels are low to begin with, so heating up the air is hard to even measure, let alone notice. It's why 60GHz is license free and used for WiGig, wireless HDMI and short haul microwave links like the ones from Mikrotik. The heavy oxygen attenuation makes it commercially worthless. Same reason why there's a license free band on 24GHz too. 24GHz suffers from water vapor absorption and has heavier attenuation than adjecent bands thanks to that. For example Ubiquiti AirFiber uses license free 24GHz.
NavinF 5y ago
Stop spreading FUD. ~60ghz radar has been used by cars for for cruise control and parking for many years now at much higher power levels than what phones can transmit. Some phones have mmWave radar for gestures too. We’d use even higher frequencies if it wasn’t for the terahertz gap.
- therein 5y ago
  Spreading FUD isn't my intention. If anything I am hoping to alleviate the FUD that open-mindedly reading these documents and plans induce in my mind. I appreciate and read the honest and detailed technical takes on the topic here. Especially acknowledging uncertainty and a healthy amount of doubt are pretty essential to the epistemological pursuit. And fear may arise when the uncertainty and doubt are not dispelled with reason.
desine 5y ago
There's also the issue that with 5G phased array antennae, tx power limits are not restricted as tightly. With a standard single tx antenna, it's easy to calculate the amount of EM energy it can create in the 3D space around the antenna. With phased array beamforming, you're using using multiple small antennae and amplifying the signal beyond the sum of the individual outputs. The safety ratings for EM radiation around phased arrays tend not to be calculated on the theoretical maximum TX power, but on the typical usage. The result is that with low enough level access to the firmware, someone could theoretically weaponize a 5G antenna to produce unsafe levels of RF energy, as well as aim the antenna without physically moving the hardware. This sounds far-fetched, and it is, but I wouldn't be surprised if we see it done in a lab, like some of the other practically infeasible but bleeding edge cool hacks.
- jdiez17 5y ago
  > With phased array beamforming, you're using using multiple small antennae and amplifying the signal beyond the sum of the individual outputs. No, that's impossible. The RF power imparted onto the EM field by any antenna array is equal to or less than the sum of the output power of each antennae.
  - MereInterest 5y ago
    I think the argument is that while the total power over the full 4π is equal to the sum of the input power, the constructive/destructive interference cause there to be higher power output within some solid angle. But my understanding is that the limit are for avoiding interference from other devices, not for human safety, and that any reasonable amount of non-ionizing radiation is incredibly safe for humans. Congestion wouldn't be impacted by the beamforming, because on average any increase in intensity at one angle would be countered by a decrease at some other angle.
    - deleted 5y ago
      [deleted]
    - marcan_42 5y ago