K6 Radio Frequency Interferance. A good call for a ham into computers.
I forgot the Bird aspect. I remember tracking seagulls until they fell out of
the sky using aircraft radars from the deck of the enferprise. then there was
the bosuns mate carying the armload of floresent tumes that just droped them
and ran when they lit up in his arms. and that was low power. only 25kw
average power :-)
--- On Mon, 8/24/09, Jeff Brown <[email protected]> wrote:
From: Jeff Brown <[email protected]>
Subject: Re: [SCFN] Cell phones and RF/microwave radiation are
identicallycarcinogenic and genotoxic
To: "SoCalFreeNet.org General Discussion List" <[email protected]>
Date: Monday, August 24, 2009, 12:07 PM
This was a fun thread! Adding to Don's example I recall reading about birds in
the Southeast US being killed upon flying into the path of radars keeping an
eye on Cuba in the 1960s...
Jeff (K6RFI)
From: donald johnson <[email protected]>
To: SoCalFreeNet.org General Discussion List <[email protected]>
Sent: Saturday, August 22, 2009 10:38:40 AM
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 <[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: Matt Fanady
To: 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, <[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
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