8 ms·
Unless there's some physical reason you can't run physical conductor there's every reason not to do this. This setup proposes to use 100mw/cm^2. That's just no
by superkuh 6y ago
Unless there's some physical reason you can't run physical conductor there's every reason not to do this.
This setup proposes to use 100mw/cm^2. That's just not acceptable unless you're sure no humans or animals are going to cross the beam (or even it's sidebands!). Even a horn has diffraction sidebands, and unless they're all at least 8dB down in all situations that's bad. The laser trips won't cover this.
This exceeds the safety standards established by the US Navy back when they were dealing with their high powered radars for the first time. They found that anything over 10mW/cm^2 can cause enough heating in animal eyes to cause clouding of the eye. Humans' deep set eyes and brow ridges help (depending on freq) but 10mW/cm^2 can still cause health issues. The measured e-field for that powerlevel, depending on wavelength, will almost certainly be above the electrical field limit for exposure in the USA. I hope that's also true in NZ.
- tyingq 6y agoFairly scary working around high power radar. Microwaves heat up the "high water content" parts of your body. Eyes, as you mention and also...testicles.
- DoofusOfDeath 6y agoPlease forgive the humor, but this immediately made a Jerry Lee Lewis song play in my head.
- interestica 6y agoSurely, since we are talking about excited water molecules, you mean "Whole lotta shakin' goin' on"...
- will_pseudonym 6y agoI'm sure that OP meant "Great Balls of Fire" https://www.youtube.com/watch?v=7IjgZGhHrYY https://www.youtube.com/watch?v=7IjgZGhHrYY
- Gene_Parmesan 6y agoYes, the person you are responding to was making a joke by playing off the fact that we all would have immediately thought of Great Balls of Fire, and then they subverted that expectation. Ergo, humor.
- will_pseudonym 6y agoLeave it to Gene Parmesan to school me. Can't believe I missed that. :)
- hugi 6y agoAn electrician working at a Radar station here in Iceland (https://en.wikipedia.org/wiki/Hofn_Air_Station https://en.wikipedia.org/wiki/Hofn_Air_Station) was stuck there overnight during a snow storm. For some reason he decided to stay in the radar room, probably since it "felt warmer". He was found properly cooked the next day. Not really an interesting story, but since I was probably 6 years old when I heard it it's stuck with me ever since and caused an everlasting fear of high powered radar.
- biofunsf 6y agoThis actually sounds a lot like an urban legend. Especially given that it’s a story you heard in your youth. I wasn’t able to find a report of that happening at the Hofn station, but the same story of this happening to an anonymous microwave technician does appear in other locales. Snopes did a debunking on these and they say it’s false: https://www.snopes.com/fact-check/nuke-of-earl/ https://www.snopes.com/fact-check/nuke-of-earl/
- hugi 6y agoYeah, most probably an urban legend. But sure stuck in my young mind :).
- tyingq 6y agoHere's a credible source for some "far short of death", but real incidents: https://academic.oup.com/occmed/article-pdf/50/1/49/4284302/50-1-49.pdf https://academic.oup.com/occmed/article-pdf/50/1/49/4284302/... Note: They are ~900Mhz, so short of "microwave", but pretty close.
- ajsnigrutin 6y agoYep... considering the skin effect, any microwave radiation would start heating the outside skin layer first, and it would hurt long before anything inside you was "cooked". If you got locked in there.. then sure... maybe.... but staying in there and not feeling it (or just feeling "warmer", until you die...) nope.
- nickt 6y ago
- deleted 6y ago[deleted]
- antpls 6y agoCould it be used on Mars or in space? There are many less living things there
- elihu 6y agoThat's my thought. One of the technical challenges of space elevators is how to deliver power to the climber. Some of the other options are to use lasers and solar panels, or to use the cable itself as a conductor. (Technically, an Earth-based space elevator would still most likely be beaming from inside Earth atmosphere, but at least it would be pointed approximately straight up and probably be positioned in the ocean or other sparsely-populated area.)
- mrfusion 6y agoI wish HN commenters would try to think of solutions instead of automatically listing the problems. This place is pretty depressing sometimes.
- rvnx 6y agoInspectors of finished works
- superkuh 6y agoWell, okay guys, I'll give you a "solution" since this is proposing to use RF anyway. Instead of doing it entirely wirelessly use a very thin conductor surface wave transmission line (SWTL). That way only one conductor is needed and the RF energy is mostly contained within a wavelength or so of the SWTL (think "inside-out waveguide). The conductor can be very thin, like 28 awg. Or, for spanning larger distance, SWTL mode has been demonstrated on twisted aluminum cord used in normal power lines. It's just a matter of adapting the coaxial to SWTL launcher (sort of cone).
- pueblito 6y agoWhat's the point of wireless power if you use a wire?
- Johnythree 6y agoExcept "Surface Wave Transmission Lines" leak. A lot.
- NortySpock 6y ago"X is a safety risk (perhaps it could be designed differently)" is a helpful safety warning to others, not just "let me list my opinion of problems". Do you harsh on people who remind you how dangerous it is to work on live electrical outlets or wear long sleeves in a chemistry lab?
- bawolff 6y agoPersonally i find people who treat everything as positive and refuse to acknowledge fundamental problems just as annoying who view things as utterly negative and only point out problems without trying to find solutions.
- cwhiz 6y agoSo sad. If only their team of physicists, engineers, and scientists had done basic internet research. Too bad. I guess they’ll plow ahead and try it out, anyway. Maybe humanity will just accidentally be a better place, despite the extraordinary negativity.
- Angostura 6y agoDo you have a better response than this snark? Perhaps by pointing out where the poster is actually in error?
- EdwardDiego 6y agoHis error is assuming that the people working on this aren't aware of the potential issues and working to resolve them. I mean, if they can't, they won't be able to deploy this system. NZ has a strong system of regulations and licensing around transmitting. Maximum exposure to non-ionising radiation is set out in NZS 2772.1, which is based on the guidelines from the International Commission on Non-Ionizing Radiation Protection. All transmitters require approval from Radio Spectrum Management, and any system like this being deployed would require a resource consent from a territorial authority under the Resource Management Act, at which point the Department of Conservation would submit on any adverse effects on local wildlife.
- cwhiz 6y agoReally? Do you think the NZ government is incompetent, Emrod is a scam, and/or PowerCo have not considered these extremely basic issues? The error by OP is assuming everyone involved in this project are morons who have yet to consider even a cursory search of the feasibility of their proposals. This is such a typical internet armchair thing to do. Point out some Google-able “flaw” and wonder aloud whether the team of scientists and engineers have considered it.
- superkuh 6y agoYou're making a few of your own assumptions here. I'm op in this thread and yes, I do think this is going to fail because of the physics of it. The free space path loss is always going to lose most of the power (ie, 40-50 dB off the top, and it's the top that matters) for any reasonable dish sizes, freq choice, and distance over 1km.
- Robotbeat 6y ago100mW/cm^2 is the same intensity as sunlight. It's not a ridiculous amount.
- hengheng 6y agoSkin is quite good at not letting sunlight through, but it's not as good at shielding RF.
- Robotbeat 6y agoSkin is translucent (at least for certain ethnic backgrounds). The heat gets in.
- the_pwner224 6y agoHave you ever gone out on a hot day and stood in the sun? There's a big difference between sun and shade. A head with black hair gets super hot, aside from the general heat you feel. Another way to say it is 1 kilowatt per square meter. It's a lot of energy. A 1500 watt electric heater can get my entire bedroom quite a bit hotter than with just the central heat running. Put 2/3rds of that energy into your body and there are certainly going to be effects.
- Robotbeat 6y agoYeah, but I think it's a reasonably safe level for power transmission through corridors where there's not supposed to be any people.
- mikedilger 6y agoSunlight is spread-spectrum. This is focused at the frequency that makes water molecules vibrate - which is why we use it for ovens.
- Robotbeat 6y agoAny heat which is absorbed causes water molecules to vibrate. Including sunlight. There's nothing particularly special about being broad vs narrow spectrum in this case.
- datameta 6y agoYour latter concern is covered in the article: "But if it works as intended, the beam won’t ever contact anything but empty air. The system uses a net of lasers surrounding the beam to detect obstructions, like a bird or person, and it automatically shuts off transmission until the obstruction has moved on."
- NateEag 6y agoOP explicitly said, "The laser trips won't cover this." That may or may not be true, but you're bringing up a point they already addressed.
- biofunsf 6y agoOP explicitly said: “Even a horn has diffraction sidebands, and unless they're all at least 8dB down in all situations that's bad. The laser trips won't cover this.” I don’t really understand this. My guess is that they’re saying that besides the targeted microwave band, other high/low frequencies will be emitted (sidebands) and that these will diffract and be way outside of the directional beam that’s protected by the laser trip wire. I would assume the inventors have at least some explanation for this, but a fluffy article won’t go into those details.
- elihu 6y agoMaybe OP meant side-lobes? https://en.wikipedia.org/wiki/Side_lobe https://en.wikipedia.org/wiki/Side_lobe
- Zenbit_UX 6y agoA horn? Like a fucking rhino? Glad OP covered that use case, I was concerned.
- phs318u 6y agohttps://en.m.wikipedia.org/wiki/Horn_antenna https://en.m.wikipedia.org/wiki/Horn_antenna 5 seconds of searching would have saved you from looking like a dick.
- temp0826 6y agoWe've obviously learned nothing from Sim City 2000's microwave power plants.
- throwaway0a5e 6y agoEveryone loves to try and score some cheap virtue points harping about safety but I don't see how a beam between two poles is worse than a live wire between two poles. Whether it's a metal line or not doesn't matter. You touch that space it's not gonna end well. The danger is constant compared to other electrical transmission and there are other benefits. Seems like a net positive so why not try it for niche use cases where its advantages make sense.
- XCSme 6y agoThe line, you can see it...
- throwaway0a5e 6y agoI think you have a fundamental misunderstanding of how live wire accidents happen and are prevented. Live wire accidents happen because people operating equipment capable of hitting the wires are looking elsewhere because looking elsewhere is a fundamental part of doing their job. The crane operator looking at the load or the helicopter pilot watching something on the ground is who hits a live wires. Not hitting live wires is caused by knowing where they are ahead of time and planning your work so you don't hit them. Making the wire invisible doesn't really change that. It's not like this tech would be used for residential lines where every Joe schmoe is operating a man-lift.
- mNovak 6y agoIgnoring all the other reasons this is unlikely to work, 8dB sidelobe level is very easily achieved though. I'm assuming they're using some sort of phased array, where SLL can be designed to <-20dB or more.
- Emrod 6y agoNo sideloabs. we are using near-field