A system like this could only work when you know in which direction the cell site is, and always turn your head in such a direction that the phone is in that direction. And then you still would need to affix the sticker on the "front" side of the phone, not conveniently on the backside.
Remember that the power being output by the phone is controlled by the cell site (it sends information about the SNR of the transmission so the phone can lower the power until that is at a low but acceptable value).
Anything you do to shield the radiation from the phone will be compensated by the phone transmitting at higher power, to achieve the same received power at the cell site.
You probably gain more by making your calls out in the open instead of behind thermally shielding office building glass. Then the phone will reduce its power so the local field strength will be less.
It is a similar situation if you have sunglasses that do ot block UV. The sunglasses cause your iris to open more letting MORE damaging UV into your eyes.
So here you shield the RF from your head and that might cause the phone to crank up the RF power making the situation worse.
They don't work. If they did, you would see one on every cell phone sold because it would be a cheap and easy way to pass the FCC SAR (specific absorption rate) tests which calculate how much RF is absorbed by your head.
You test if the device works easily enough. Find the location of your local cell tower. Locate the phone on your head on the side opposite the cell tower (i.e. with your head in the way of the RF path). If you're still able to talk via the cell tower in this position, the sticker isn't blocking any RF.
The sticker would be better because it marks you as a likely customer for other scams. For example, have you looked into cell tower Orgonite "gifting" which cleans up electromagnetic pollution?
Metal foil also doesn't work. It reflects the RF while what you really want is something to absorb the RF. What you really want is a carbon foam absorber:
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Not dropping dead, but there are studies that say people who get brain cancer _and_ made a lot of phone calls during an extended period of time prior to the diagnosis, have a higher probability that the tumour is at the side where they use to hold their phone.
Outcomes like these scream for epidemiological studies on a much larger scale, e.g.: like the ones that proved the health damage from _factory produced_ (i.e. from chemically treated tobacco) cigarettes.
The funny thing that I'm trying to point out here, is that nobody has ever proven that smoking pure organic and untreated tobacco (except drying and storing of course) as the native American Indians seem to have done, is dangerous to your health.
The recommendation for people who make wireless phone calls for extended periods of time daily is to use a head set and keep a distance of a few cm (one inch?) between the phone and any body part.
Hey it's only one data point, but I like lotsa garlic, and I've yet to met a vampire. (I was making spaghetti sauce on Sunday... my hands still carry that garlic smell....)
Actually, they do. Cell phones use high efficiency power amplifiers fully saturated (no change in output power when input power is varied). The output amplitude is controlled by varying the supply voltage for the output stage - bandwidths into the 40 MHz range are available.
The phones communicate using a Quadrature Amplitude modulation scheme (various symbol encodings are assigned on the fly).
Phase is controlled in low level circuitry. Various symbols are accessed by setting drive phase (0/180, 90/270) and relative I and Q amplitude at the output stage.
Sneaky people have started recovering the power returned from the output combiner terminating resistor (using vhf switchers instead of actual resistors).
Setting output power is no more difficult than assigning low power symbol encodings - done all the time, automagically.
I assume that you forgot to post a link to the product that you were actually interested in :-).
Anyway, if you are concerned about the radiation from your cell phone, just look at the signal strength indicator on your cellular phone.
If you get full signal from your base station, your mobile handset will use the minimum power to contact the base station.
Thus go outside to start a new call or receive a call to get the best cell power reading, which also minimizes the EM field radiated by your mobile phone.
One of the worst deficiencies of the NMT450 cellular network (early
1980's) was that you could not turn down the cellular phone below 1 W, all modern phone systems will adjust the cellular power to match a two way connection.
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