6 ms·

I'm highly skeptical of the 60% efficiency figure being any sort of end-to-end metric. I suspect that was poorly phrased, and the receiver/rectifier was operati

by mNovak 4y ago

I'm highly skeptical of the 60% efficiency figure being any sort of end-to-end metric. I suspect that was poorly phrased, and the receiver/rectifier was operating at 60% efficiency (which is reasonable for RF rectifiers), of power incident. But the vast majority of power loss is happening along the path before reaching the receiver. Some ballpark numbers: 1km at 10GHz is ~110dB of path loss. Those look like feasibly 40dBi antennas at both ends. That still leaves -30dB link budget, i.e. 0.1% of energy reaching the target.

apcragg 4y ago
I'm also not convinced that they're even out of Far-field. That looks like a roughly 5m dish, which at 10GHz is still in the radiating near field at 1km. I wouldn't be surprised if the main lobe is entirely incident on receiving aperture. That's a neat demo but it does not demonstrate truly radiating power between two distant points. They've essentially built a fancy a wireless cellphone charger. 60% is also almost certainly not total system. A portable antenna like that by itself, with no path loss or other losses, would likely have an aperture efficiency of about 60%. A planar patch antenna like the one used to receive would be similar.
toephu2 4y ago
From the YouTube comments: Video carefully avoids to state that the overall efficiency of the system is 1.8%. Input power was 91.2kW at the TX antenna, out of which 1.65kW was produced at the receiving side. https://ieeexplore.ieee.org/mediastore_new/IEEE/content/media/9171629/9673801/9662403/roden.t2-3130765-large.gif https://ieeexplore.ieee.org/mediastore_new/IEEE/content/medi...
- uuyi 4y ago
  I’m not sure why people get excited about this. Putting 92kW in for a 47dBm over 1km is comedic levels of loss. It’d be more efficient to move a 2kW generator over and send several people on laps with pogo sticks carrying thimbles full of diesel to keep it running. I all really tired of all the unicorn shit being shoveled in the wireless energy transfer research area.
  - hilbert42 4y ago
    Neither am I for precisely the same reasons. Ten points for your brilliant description about efficiency, it beats my long technical diatribe by miles. :-)
  - LB232323 4y ago
    Because you have to start somewhere, if these technologists took these armchair physicist internet comments to heart, then what progress would they make? Having worked for defense technology contractors in the area, these people want ideas. They want brand-new, sci-fi level ideas. These militaries and defense companies will literally hire sci-fi writers for inspiration. It's not like SV where the primary focus is profit. It's less limited than that, these researches are on the cutting edge, it's where we received the internet itself. Remember, researchers in this league led the use and development of radio in its early stages for military reasons. The truth is, in order to attract defense funds, you have to oversell an idea way, way down the line. Imaginative people with bold ideas of the future. It's beyond market trends, publicly-funded technological development is pure and machine-like. Blows any selfish, boyhood fantasies of the world's richest men out of the water.
    - uuyi 4y ago
      This is optimist fantasy hyperbole. You can’t imagine physics into existence. And also the military is well known for spending on ideas that don’t even have a hope of working out whatsoever. We can use goat staring as a fine example of military thinking. Having also worked for clearly larger and more respectable defence contractors, one of whom had a big stake in early radio, in an RF engineering capacity, this stuff is laughed off the table. No one really wants or needs this capability nor believes it will work. It’s fringe garbage. Defence projects start with capabilities and then work out what you can deliver within those capabilities and client expectations. Knowing when to tell the client they are lunatics rather than taking the money and dragging a project out while paying subcontractors is where things are divided in the market.
      - iancmceachern 4y ago
jhallenworld 4y ago
Lasers have much higher "antenna" gain. How about using an IR laser to remotely heat a steam engine which runs a generator... I bet overall efficiency is at least an order of magnitude higher.
- downrightmike 4y ago
  Basically, the more things change the more they stay the same: https://history.howstuffworks.com/historical-figures/archimedes-death-ray.htm https://history.howstuffworks.com/historical-figures/archime...
  - spacemark 4y ago
    Can we kill the "genius" trope already? In 15 years at the nation's best engineering schools and another 10 at companies and institutions that employ their graduates, I have yet to meet a nobel prize winner, CEO, professor, astronaut, politician, or other individual that is single-handedly "propelling global human advance." Perhaps these magical minds are hiding under some rock I haven't overturned yet, but it's much more likely that the "genius" model is just not a very good one. There are plenty of clever people around and there will always be a tail end of the bell curve, but the idea that these individuals are lifting up the rest of us is self-serving and ironically, demonstrably false. It's hero culture for intellectuals. There are plenty of humans with tail-end IQ, none of whom become anything without the rest of society getting up and going to work to support investment in their minds and the infrastructure that enables them to utilize their capacity. Einstein would have been nothing without cooperation from a wide range of scientists, mathematicians, family members, and hell his garbage man. /end rant Thank you for sharing that link, though - the bit about reproduction has some meat to it. I've wondered whether innovation will slow as global population levels off. We'll get better at being efficient with the capacity we have, to be sure, but I wonder if eking out efficiencies will also asymptotically stall.
    - downrightmike 4y ago
      I think that we don't meet many geniuses because they are off doing their own thing in research labs. Look at MRNA vaccines, just a few people toiling for decades have saved millions of lives. But fret not, innovation should only continue as more people are brought up and educated than we've ever been able to in the past. Incremental change will get more helpers. Plus we aren't stunting generations with lead poisoning by and large anymore, which certainly reduced the amount of minds that can handle super specialized endeavors.
pharos92 4y ago
This is the comment I came here to see. Thankyou.

by mNovak 4y ago

apcragg 4y ago

I'm also not convinced that they're even out of Far-field. That looks like a roughly 5m dish, which at 10GHz is still in the radiating near field at 1km. I wouldn't be surprised if the main lobe is entirely incident on receiving aperture. That's a neat demo but it does not demonstrate truly radiating power between two distant points. They've essentially built a fancy a wireless cellphone charger. 60% is also almost certainly not total system. A portable antenna like that by itself, with no path loss or other losses, would likely have an aperture efficiency of about 60%. A planar patch antenna like the one used to receive would be similar.

toephu2 4y ago

From the YouTube comments: Video carefully avoids to state that the overall efficiency of the system is 1.8%. Input power was 91.2kW at the TX antenna, out of which 1.65kW was produced at the receiving side. https://ieeexplore.ieee.org/mediastore_new/IEEE/content/media/9171629/9673801/9662403/roden.t2-3130765-large.gif https://ieeexplore.ieee.org/mediastore_new/IEEE/content/medi...

uuyi 4y ago
I’m not sure why people get excited about this. Putting 92kW in for a 47dBm over 1km is comedic levels of loss. It’d be more efficient to move a 2kW generator over and send several people on laps with pogo sticks carrying thimbles full of diesel to keep it running. I all really tired of all the unicorn shit being shoveled in the wireless energy transfer research area.
- hilbert42 4y ago
  Neither am I for precisely the same reasons. Ten points for your brilliant description about efficiency, it beats my long technical diatribe by miles. :-)
- LB232323 4y ago
  Because you have to start somewhere, if these technologists took these armchair physicist internet comments to heart, then what progress would they make? Having worked for defense technology contractors in the area, these people want ideas. They want brand-new, sci-fi level ideas. These militaries and defense companies will literally hire sci-fi writers for inspiration. It's not like SV where the primary focus is profit. It's less limited than that, these researches are on the cutting edge, it's where we received the internet itself. Remember, researchers in this league led the use and development of radio in its early stages for military reasons. The truth is, in order to attract defense funds, you have to oversell an idea way, way down the line. Imaginative people with bold ideas of the future. It's beyond market trends, publicly-funded technological development is pure and machine-like. Blows any selfish, boyhood fantasies of the world's richest men out of the water.
  - uuyi 4y ago
    This is optimist fantasy hyperbole. You can’t imagine physics into existence. And also the military is well known for spending on ideas that don’t even have a hope of working out whatsoever. We can use goat staring as a fine example of military thinking. Having also worked for clearly larger and more respectable defence contractors, one of whom had a big stake in early radio, in an RF engineering capacity, this stuff is laughed off the table. No one really wants or needs this capability nor believes it will work. It’s fringe garbage. Defence projects start with capabilities and then work out what you can deliver within those capabilities and client expectations. Knowing when to tell the client they are lunatics rather than taking the money and dragging a project out while paying subcontractors is where things are divided in the market.
    - iancmceachern 4y ago

jhallenworld 4y ago

Lasers have much higher "antenna" gain. How about using an IR laser to remotely heat a steam engine which runs a generator... I bet overall efficiency is at least an order of magnitude higher.

downrightmike 4y ago
Basically, the more things change the more they stay the same: https://history.howstuffworks.com/historical-figures/archimedes-death-ray.htm https://history.howstuffworks.com/historical-figures/archime...
- spacemark 4y ago
  Can we kill the "genius" trope already? In 15 years at the nation's best engineering schools and another 10 at companies and institutions that employ their graduates, I have yet to meet a nobel prize winner, CEO, professor, astronaut, politician, or other individual that is single-handedly "propelling global human advance." Perhaps these magical minds are hiding under some rock I haven't overturned yet, but it's much more likely that the "genius" model is just not a very good one. There are plenty of clever people around and there will always be a tail end of the bell curve, but the idea that these individuals are lifting up the rest of us is self-serving and ironically, demonstrably false. It's hero culture for intellectuals. There are plenty of humans with tail-end IQ, none of whom become anything without the rest of society getting up and going to work to support investment in their minds and the infrastructure that enables them to utilize their capacity. Einstein would have been nothing without cooperation from a wide range of scientists, mathematicians, family members, and hell his garbage man. /end rant Thank you for sharing that link, though - the bit about reproduction has some meat to it. I've wondered whether innovation will slow as global population levels off. We'll get better at being efficient with the capacity we have, to be sure, but I wonder if eking out efficiencies will also asymptotically stall.
  - downrightmike 4y ago
    I think that we don't meet many geniuses because they are off doing their own thing in research labs. Look at MRNA vaccines, just a few people toiling for decades have saved millions of lives. But fret not, innovation should only continue as more people are brought up and educated than we've ever been able to in the past. Incremental change will get more helpers. Plus we aren't stunting generations with lead poisoning by and large anymore, which certainly reduced the amount of minds that can handle super specialized endeavors.

pharos92 4y ago

This is the comment I came here to see. Thankyou.