Cool, I got schooled. J
Thanks for the info, Don. From: [email protected] [mailto:[email protected]] On Behalf Of donald johnson Sent: Saturday, August 22, 2009 10:39 AM To: SoCalFreeNet.org General Discussion List Subject: Re: [SCFN] Cell phones and RF/microwave radiation are identicallycarcinogenic and genotoxic Microwave cooking. interesting subject. When I was much younger I read about the soldiers that were standing watch at the DEW Line radars in Greenland. They loved to stand in front of the radars because they would get warmed up by the radar energy. As far as I know though no one was killed by this but I always wondered what their kids looked like. To get the wavelength of the emission you take 300 and divide the frequency into it. this will give you whe wavelength in meters. multiply that by 39.37 and that will give you the wavelength in inches. So 300/1900*39.37=6.21 inches not the 2 inches mentioned earlier. Any gap of more than 5% of a wavelength will allow some leakage. In fact any gap at all will leak BUT the amount is considered negligible until more than 5% of a wavelength. This is why many of the old UHF television antennas had a dish that was made up of a wire mesh. less metal to have to pay for and it picked up 95% of the signal. 5 % gap means that you need to have holes that are less than .31 inch in size at 1.9 GHZ cell phone frequency’s, and about .29 inches at 2.4 GHz. this also means that if your door has more than a .3 inch gap in it that your oven (2.4GHZ) will also leak some. The door gaskets do have copper or aluminum in their construction so they are required to be complete and unbroken to work properly. If you do have a large gap or crack in the door gasket then get them repaired or replaced for 2 reasons. 1) Personal safety 2) Your wireless lan will not like the interference as the oven has 1000 watts and your lan has .1 or less and they are on nearly identical frequency’s, close enough that they will and do jam wireless lans when someone is cooking something. I am a Ham Radio operator (WD6FWE) as well as an RF Engineer with a radiotelephone licience. Don Johnson --- On Thu, 8/20/09, Steve Shapery <[email protected]> wrote: From: Steve Shapery <[email protected]> Subject: Re: [SCFN] Cell phones and RF/microwave radiation are identicallycarcinogenic and genotoxic To: "'SoCalFreeNet.org General Discussion List'" <[email protected]> Date: Thursday, August 20, 2009, 6:18 PM When I worked for a certain unnamed ghetto cellular provider, we were forced to take RF Safety training… and we were issued badges similar to the ones used in nuclear power plants. Based on what we saw in the training, being up on a standard CDMA tower when it was hot (i.e. violating lock-out/tag-out laws) you could get a third-degree burn in a few seconds. Not something I’d want to mess around with, personally. However, this was cooking along around 100W, which is about 1,000 times more powerful than a decent access point will deliver. This BTW, is based on 1900Mhz technology, which should result in about 2” wavelengths, if my math is right. And Matt – based upon some quick research, it appears that most microwave ovens in the US run around 2450Mhz, which, as you said, results in a wave approx. 4 inches in size. So, unless you have a GAPING hole in your oven, you should be relatively safe. However, if you put a big antenna on your cordless phone….. From: [email protected] [mailto:[email protected]] On Behalf Of Matt Fanady Sent: Thursday, August 20, 2009 5:26 PM To: SoCalFreeNet.org General Discussion List Subject: Re: [SCFN] Cell phones and RF/microwave radiation are identicallycarcinogenic and genotoxic While I am by no means an expert on the subject, it is my understanding that a microwave oven is always safe, unless there are large gaps. Seeing as how the wavelength of 2.4 GHz microwaves are measured in INCHES, there would have to be a rather significantly gaping hole in a microwave in order to let enough of these waves out to cause harm (or even significant interference). This is why you can have a clear plastic window on the oven door, with only the perforated metal screen between you and the radiation. The waves are simply too large to make it through these holes. The rubber seal around the door to the best of my knowledge performs no radiation containment function. -M@ On Thu, Aug 20, 2009 at 5:19 PM, TomC < <http://us.mc825.mail.yahoo.com/mc/[email protected]> [email protected]> wrote: Generally good thinking. Commercial radio & TV radiating sources (antennas) are dangerous and in most cases are fenced -- to protect you as well as themselves. YES Radio and TV stations are licensed and one can assume are safe to be around their antenna providing you are not violating posted warnings and fences. This is not the case in Mexico. Also there are game/entertainment devices that radiate low levels that are safe to hold and use -- like that cell phone and Bluetooth are FCC approved as safe. There is some disagreement here regarding cell phones held close to the brain all day long. I worry about the radio frequency radiation I might be getting from my microwave oven and do not stand close by. Ovens have gaskets that help but also get old -- and are not monitored my anyone as to leakage. There is always leakage but the distance 1-2 feet is safe --when the oven is new. These are high power devices and ironically it is the eyes that are hit by high leakage if a malfunction should occur. One can buy cheap microwave detectors to measure leakage. Also I would never buy a house under or less than 300 feet from big tower high voltage power lines. This issue is open, Good question. Tom (I hold FCC radiotelephone license, many years in broadcast transmitter/antenna business.) ----- Original Message ----- From: <http://us.mc825.mail.yahoo.com/mc/[email protected]> Matt Fanady To: <http://us.mc825.mail.yahoo.com/mc/[email protected]> SoCalFreeNet.org General Discussion List Sent: Thursday, August 20, 2009 3:49 PM Subject: Re: [SCFN] Cell phones and RF/microwave radiation are identicallycarcinogenic and genotoxic Its really only dangerous when you're up close, and even then, its not dangerous as in "its going to give you cancer" dangerous, the most vulnerable part of your body to high power high frequency RF is the cornea of your eyes. This is because RF generates heat when it comes into contact with organic material, the same way a microwave oven generates heat. The cornea lacks sufficient blood flow to carry this heat away, so they are the first thing to "cook". But this is only true when you're very close to the source, and even then, the risk is minimal. -M@ On Thu, Aug 20, 2009 at 3:34 PM, < <http://us.mc825.mail.yahoo.com/mc/[email protected]> [email protected]> wrote: Hi Bao. The cellular equipment you found is an example of a major RF transmitting facility under the jurisdiction of the FCC. Typical facilities include radio and television broadcast stations, satellite-earth stations, experimental radio stations and certain cellular, PCS and paging facilities. The warning sign you found helps define a keep-out area near the transmit antennas such that unknowing persons are protected. These facilities are required to undergo routine evaluation for RF compliance whenever an application is submitted to the FCC for construction or modification of a transmitting facility or renewal of a license. Failure to comply with the FCC's RF exposure guidelines could lead to the preparation of a formal Environmental Assessment, possible Environmental Impact Statement and eventual rejection of an application. Technical guidelines for evaluating compliance with the FCC RF safety requirements can be found in the FCC's OET Bulletin 65. In short, the keep-out areas provide a safe buffer away from strong transmitters. The cell transmissions from different nearby basestations are not really additive. They transmit in different bands, or on different channels within those bands. Hope this helps. Regards, Brian C. Gallagher RF Hardware Engineer Vehicle WLAN Development _______________________________________________ SoCalFreeNet.org General Discussion List To unsubscribe, please visit: <http://socalfreenet.org/mailman/listinfo/discuss_socalfreenet.org> http://socalfreenet.org/mailman/listinfo/discuss_socalfreenet.org -----Inline Attachment Follows----- _______________________________________________ SoCalFreeNet.org General Discussion List To unsubscribe, please visit: <http://socalfreenet.org/mailman/listinfo/discuss_socalfreenet.org> http://socalfreenet.org/mailman/listinfo/discuss_socalfreenet.org
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