Why “Radiation Sheild” Chips, buttons and stickers can’t work
October 30th, 2009
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There are a number of products out there which claim to “absorb” or “scramble” the electromagnetic radiation that is emitted by phones, wireless networking devices and other RF products. Whether or not there’s any reason to worry about these emissions is another topic entirely, but the fact of the matter is that these devices don’t work and can’t work. The products in question include stickers, buttons, bracelets, necklaces, pendants and other various charms, trinkets and small items. They claim to “scramble” or “shield” the wearer from the electromagnetic emissions of their device.
The problem is that they defy the laws of physics. Radio waves and microwaves, along with lower frequency electromagnetic waves, are all part of the electromagnetic spectrum, the same spectrum that includes visible light and infrared. Their wavelengths are longer and their frequency is lower, but otherwise, radio waves are the same as light.
If it were possible to use a device like a pendant to absorb or shield radio waves, then it would also be possible to have a “dark bulb” that reduces ambient light in an area when turned on. However, this is not actually possible. Short of a black hole, there’s no way to “suck up light” or otherwise pull the ambient light out of an area. Some 3D rendering engines do have “light suckers” or “inverse lighting” options, but these do not exist in the real world.
Just like light, the only way to reduce any electromagnetic radiation is to have a shield of some kind between the source and the area that you want to reduce the radiative flux in. The shield must be large enough to cover the area you want to shade. Depending on the distribution of the light (or radio waves) the shield may cast a shadow larger than itself, but it must be oriented so that the shadow covers the entire area.
Therefore, wearing a necklace with a pendant that is supposed to block radiation makes as much sense as wearing a pendant with the expectation that it will surround your body with darkness and stop you from getting a sunburn, or for that matter, being able to see what is around you, since the light would be “sucked up” before getting to your eyes.
Shielding yourself from electromagnetic radiation in the RF portion of the spectrum is not especially difficult, however. Just like you could shield yourself from light by warping yourself in black sheets, you can shield yourself from RF radiation by covering your body in a material that blocks the radiation. For light to be shielded, the material must be solid or at least close to solid, with only microscopic gaps between molecules. However, the wavelength of radio waves is much larger, so a material with holes in it is fine, as long as they are smaller than the wavelength of the emissions being blocked. In practice, this can take the form of a wire mesh or screen-like material.
Shielded areas are known as “Faraday cages” and are common in applications where external RF interference must be blocked. The Faraday cage must not have any gaps in it larger than the wavelength of the signals being blocked or they will get through. Ideally, a Faraday cage should be grounded to prevent it from re-radiating the signals and should be made of a conductive material such as copper or aluminum. Alternatively, simply having a large amount of dense material like concrete, water or soil will also work to block electromagnetic waves of all kinds, but much more will be needed than the Faraday cage approach. You can buy RF-blocking suits that you can wear and will effectively block your entire body, but you will also look like a bee keeper. It is also possible that such an approach could block the radiation from a phone, but it would have to cover the entire phone and would also prevent it from working, as the signals would not be able to reach the towers.
On the topic of destructive interference:
There is one narrow circumstance where a device could theoretically intercept or block RF radiation without having physically block it, but this is a narrow area that would NOT work for the circumstances these products claim to be used for. Destructive interference is the process by which two waves 0f equal frequency and amplitude but opposite phase meet and cancel each-other out, and in theory this can be used to remove unwanted electromagnetic waves, but only in narrow circumstances.
Since waves move through space, waves originating at different points will not always be synchronized for phase. This only occurs at a few narrow regions in space. At other points, the signals will have little or no effect on each other or will amplify each other. Phased arrays of antennas make use of this to increase signal gain, but in order for this to work, the elements have to be in a specific place in space and oriented properly to the signal being received. Another application that makes use of interference is interferometry. Interferometers can block unwanted waves and increase chosen ones by combining the wave phases. However, for interferometers to work properly, they have to be aligned to within a fraction of a millimeter or the waves will not meet properly.
Therefore, even if these devices could produce a signal to interfere with the waves of undesired electromagnetic radiation, they could not reduce it except at a few tiny points. However, there are even more problems with this concept. For one thing, the devices would need an active transmitter to produce the signals necessary and would also need a means of predicting the emissions from a device before each wave is even transmitted. Devices like cell phones and wireless networking routers modulate their radio waves to carry information, thus making continuous changes to the frequency distribution of the waves. A device which transmits signals to interfere with these would need to transmit at an identical frequency, such that the waves meet each other as perfect mirror images of each other, but to do this, the device would need to know what frequency and amplitude each wave was even before it was transmitted to allow time for them to combine.
There is one application in which active destructive interference works and that is active noise canceling, but this is a much different set of circumstances. Acoustic waves are much much lower frequency than radio waves and thus there is enough time for a microprocessor to sample and calculate a response to the waves. This technique also must predict the sound waves before they reach the destructive waves, but this can be done by making use of the fact that most noise sources produce a continuous type of noise, such as a drone or hum. Active noise quieting is therefore not feasibility for high frequency, varying noises.
This entry was posted on Friday, October 30th, 2009 at 12:27 pm and is filed under Bad Science, Good Science, Not Even Wrong, inverse square. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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October 30th, 2009 at 2:57 pm
I’ve been involved with RF since I was 10 years old. First with Amateur Radio, and then as a career. I’ve been exposed to everything from LF to MM Waves at varying power levels, always taking the standard precautions, and in particular, protecting my eyes.
I have suffered NO ill effects from almost 50 years of exposure.
It always cracks me up when I see these “devices” being promoted to “protect” you from RF. You might as well wear a burlap sack of burnt chicken bones around your neck!
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October 30th, 2009 at 4:15 pm
Hahaha!!! awesome. I didn’t even know that “radiation shields” were a thing!
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October 30th, 2009 at 4:28 pm
It is unfortunate that consumer protection laws do not require that the manufactures of these devices prove that they hold up to their claims in laboratory tests.
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October 30th, 2009 at 6:50 pm
My sister had a sticker on her phone that was supposed to be a “radiation scrambler.” I tried to explain to her that it was worthless and the only way to block radiation was to make the phone inoperative and that it didn’t matter anyway, but I’m not sure if I got through to her or not. She took the sticker off, but I think she may have stuck it back on after I left. She didn’t throw it out, I know that much.
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October 30th, 2009 at 9:02 pm
Maybe they should sell fine wire mesh that people can wear over their heads while making phone calls.
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October 30th, 2009 at 10:51 pm
The last year has been an enlightening lesson in just how hard it is to make a box that can shield RF radiation. It’s not easy and requires a large bag of tricks like spring loaded fingers on panel seams, grounding everything, breaking lines of sight and hex perfmetal. Even then we just barely passed the sensitivity tests, which was not a surprise, especially when you have to deal with vents and openings. To try to shield emf with necklaces and beads is ridiculous. But the gullible will buy anything. I used to sell these shield thingys as counter toys in a hardware store and people would buy them even when I would tell them that they would not work. I could never convince them that the if the shields worked, the cell phone wouldn’t.
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October 31st, 2009 at 2:03 am
J Carlton said:
I assume you needed to make a box that somehow was able to shield equipment from RF and at the same time maintain some kind of functionality or interface, because otherwise you could just pile a whole mess of metal on it. But yeah, if you want to actually make it good enough to block signals that would interfere with something that can be very difficult. Often you can find components that are individually shielded themselves. That’s how most products are manufactured – with the tuner shielded and not the whole unit.
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October 31st, 2009 at 2:52 am
Very well written, and I really like the “dark bulb” because it shows exactly why this can’t work in a way that hopefully some people I am sending this to will understand. You don’t really need to worry about this stuff anyway, but even if you did want a shield, no necklace or bracelet or pendant will do it any more than a bulb that makes the room dark.
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October 31st, 2009 at 10:22 am
There’s been much talk recently about wireless power transmission (WiTricity, WREL and others).
http://en.wikipedia.org/wiki/Resonant_energy_transfer
This is yet another physical phenomenon with a cool name that could be used to market bogus “radiation absorbers”. I think resonant energy transfer is distinct enough from either shielding or destructive interference that you might want to expand your article to cover this one too.
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November 1st, 2009 at 12:40 pm
You forgot to mention the ever-popular tin-foil hat.
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November 1st, 2009 at 10:00 pm
I’m not sure one way or the other about EM radiation, but its no surprise you would dismiss all these worries out of hand. If small amounts of radiation from nuclear plants and disasters caused harm propotional to large doses, then that would massively increase the damage of Chenobyl and long term leakage from the now thankfully cancelled Yucca Mountain. So of course Dr.Buzz must hold the belief, that there is some magical threshold at which radiaiton (both alpha/beta waves and electromagnetic) do not cause damage. I admit that we cant shut down all nuclear plants now but they are not a long term solution since there is no long term waste stotrage facility and reprocessing is not going to happen.
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November 1st, 2009 at 10:25 pm
Bruce – You repeat the same stupid things over and over and refuse to educate yourself enough to carry on an intelligent conversation.
I have come to the conclusion that you are nothing but a troll. I will not waste my time replying to your posts, and I suggest no one else does.
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November 1st, 2009 at 10:33 pm
bruce said:
Not that it has to do with the discussion at hand or the fact that ionizing radiation is different than RF radiation or the fact that this is being steered toward something irrelevant… But I would like to make sure I do not allow one thing to go without refuting it.
I do not dismiss the worries “out of hand” and I do not “believe” that there is a “magic” threshold of anything, nor do I find this an ideological issue. I base this conclusion on the avaliable data, which is very extensive, including some studies which were very large and extremely high quality. I also base it on the theory and the fact that no known mechanism exists or reason to presume this.
There exists no empirical data to support the “worries” and the subject has been studied extensively. We can now saw without doubt that these levels of radiation do not cause harm to tissue in vitro or to animals. If we are to say that humans are harmed, we must assume that humans are somehow unique in their susceptibility to this by some means unknown and for reasons unknown. We must also reject decades of tested established theory.
Had you asked me three or four years ago whether or not cell phones cause cancer, my answer would have been similar to what many say “I don’t know that there is any evidence that they do, but they might. There’s a a chance they do. I don’t really know.”
The reason my response would be different today than it would have been in 2004 or something is that as I’ve examined these claims I’ve spoken with a lot of people who know way more about this than I do, I’ve read a lot of study data, I’ve looked at a lot of historic and scientific information.
There is no magic threshold, there is a thermal threshold. It is the level where tissue can be heated to the point of damage. This is the inescapable conclusion.
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November 1st, 2009 at 10:34 pm
bruce said:
You know, Bruce, your habit of coming out with these statements where you obviously know nothing about the subject matter, and haven’t bothered to do any research on it keep dropping your credibility level. It’s kind of sad, really – I wonder why you keep on doing it.
A very easy example of this: alpha and beta radiation aren’t waves, alpha radiation is helium nucleii with the electrons stripped off, while beta radiation is electrons or positrons, depending on whether it’s positive or negative. If alphas don’t get through the surface of your skin, they can’t hurt you, and unless you are dealing with a very unusual source at close ranges, the damage is comparable to walking between two neighbouring buildings on a sunny day. Betas are a touch more dangerous, but their effective range is much lower (they interact with air and lose their energy).
As an easy test of the Linear non-Threshold Hypothesis, check cancer rates among radiologists and airline pilots, which are probably two of the highest rad exposure jobs you can find. I won’t do the research for you on this – you’ll just accuse me of lying. Go find and read the cancer rate studies. I expect to see valid statistical analysis (methodology included, please) with citations of all the relevant material – the same standard I would expect from any intelligent person approaching this seriously.
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November 2nd, 2009 at 6:53 am
There is a (small) problem phone users don’t generally think of: with modern internal antenna small cellular phones, it is easy to put several fingers over the antenna, causing an unwanted absorbtion and potentially (that is, if your head is not already in the way to the base station) forcing the phone to emmit at higher power. Anyway, if you really want to reduce exposition to your phone while using it, use its earplug, stay in an elevated clear area and hold the phone between two fingers with your arm raised, and yes, I know, you’ll really look ridiculous.
Personally, I keep mine in my pant front pocket.
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November 3rd, 2009 at 3:02 pm
The reason my response would be different today than it would have been in 2004 or something is that as I’ve examined these claims I’ve spoken with a lot of people who know way more about this than I do, I’ve read a lot of study data, I’ve looked at a lot of historic and scientific information.
There is no magic threshold, there is a thermal threshold. It is the level where tissue can be heated to the point of damage. This is the inescapable conclusion.
Ok, so lets assume you are right about the thermal threshold, which I guess applies to microwave type radiation. There are some forms of electronic radiation which can cause cancer, such as living next to high voltage power lines. The state of California has officially issued research findings demonstrating these risks.
http://www.ehib.org/emf/RiskEvaluation/riskeval.html
So at high levels, there exists this risk of cancer, but at low levels it suddenly drops off to zero? What, exactly, is the level where the risk suddenly disappears?
You repeat the same stupid things over and over and refuse to educate yourself enough to carry on an intelligent conversation.
You seem to believe “educate” means to accept your beliefs whole sale, if I think skepticaly, for myself and come to other conclusions then I am not.
As an easy test of the Linear non-Threshold Hypothesis, check cancer rates among radiologists and airline pilots, which are probably two of the highest rad exposure jobs you can find. I won’t do the research for you on this – you’ll just accuse me of lying. Go find and read the cancer rate studies. I expect to see valid statistical analysis (methodology included, please) with citations of all the relevant material – the same standard I would expect from any intelligent person approaching this seriously.
So you claim, but there seems to be a proponderance of studies linking airline pilots to a higher cancer rate. I suppose all the studies demonstrating this link are “no good.”
http://www.cancerhelp.org.uk/about-cancer/cancer-questions/airline-staff-and-cancer
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November 3rd, 2009 at 6:14 pm
Bruce said:
*****SIGH*****
Bruce said:
The increase found in the afore mentioned study was very small and the distribution was not entirely consistent with the radiation exposure. It is likely lifestyle factors. Airline crews may travel more and that means more time in the sun. They may be more likely to smoke. They spend more time in an enclosed enviornment breathing the same air.
Last I heard, there is no empirical evidence of cancer increases under a few hundred millirem.
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November 4th, 2009 at 3:08 am
Very good point. I always figured those necklaces and the chips you are supposed to put on your phone are scams. They sell them in the local drug store near me called the Q-link and it sounds like pure snakeoil. It says it makes you feel more alert, improves your imune system, reduces body and head aches and so on by protecting you from the radiation from your phone or computer. It sounds like a fantasy to me. I don’t even think that those things really are the cause of that kind of thing.
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November 6th, 2009 at 2:11 am
You are so full of **** and this site is so clearly a front for every big corp from phones to nukes and chemicals. Phone radiation is VERY VERY bad for you. You sound like the ppl in the 1950’s who said smoking was fine. Same thing allover again.
I don;’t know if the chips make the cell phones better it is probably like filtered cigarettes, like they may be not quite as bad, buit really you should just not smoke if you want to be healthy and not talk on the phone either. I mostly just txt now a days andn hold the phone away from my body. Less radiation that way.
You’re better safe than sorry. I don’t trust these companies and it doesn’t seem reasonable to me that all that radiation could be so harmless.
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December 1st, 2009 at 3:45 am
I have been studying the biofield of the human body for 12 years now and also the effects of EMF’s. When I began to research this area with another doctor, I was involved with a project for 7 years and then more on my own in trying to help stop the weakening effects of EMF’s upon the body. These fields can not be stopped, but they can be tested upon the body and seen in the central nervous system on recorded on biofeedback equipment called EAV. it’s amazing how accurate it is. We were able to develop some devices that are proven to remove the stress from the body and it can be recorded on EAV and Thermolgraphy! They naysayers can talk all they want about how these devices don’t work…however it is too late to try and convince me of this because I have personally watch people get well and get rid of all kinds of problems and pains, etc. using the devices we have been able to produce. Check it out and say anything you want…we have the proof: http://www.safeconnectplus.com
Sincerely, Jody Ryabinov
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December 9th, 2009 at 8:37 pm
The gadgets all work just fine for the people who sell them, and they fulfill their intended purpose — to fill their bank accounts.
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January 11th, 2010 at 5:36 am
To the author :
To have a full insulation from electromagnetic fields, you would also add to the Faraday Cage a layer of high permeability material, like mu-metal, to also stop the magnetic field.
To believers of small magical radio frequency absorbers :
If the phone can’t receive the right amount of RF power from antenna, it will increase the emission power, emptying faster the battery and sending your head more RF power…
The power of the relay antenna is far less than the power of the phone close to your head.
If you are afraid, find a long wood stick, attach the phone to the end, and try to raise it the more you can in the sky : efficiency of antenna reception will be better, thus emitting less. Just find an earplug with long wire.
You may add a nice flag to the stick, to add beauty to the view
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January 11th, 2010 at 5:43 am
Hi,
Matthew said:
This part is wrong, any particle has a corresponding RF field propagating with it. See http://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality
Even fullerene has attached wave…
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