Folks,
Very interesting stuff. I have used the ARRL Book *RF Exposure and You *as
my guide. Just in case a neighbor ever asks I have actually complete a
document for each band that I use and up date it as rigs or antennas change.
It has been interesting to realize that the issue is ERP (EiRP) and not
how much power comes out of the power amplifier. It has has been
interesting to realize that once at 10 meters and above things start to get
a little more complicated. 160-10 I am a "100 watts and wire" kind of ham
and that is pretty benign. But even with 100 watts into a 10 meter
vertical the uncontrolled access radius is surprisingly large. Six hundred
watts into a Yagi on 6m yields some surprising results, at least to me.
And then there is the issue of my attic antennas and my dear wife sleeping
away what maybe 8 feet below them as I pull a contest all night stint!
All good stuff and it makes the hobby a little more interesting.
John K4SQC
On Thu, Mar 21, 2019 at 5:41 PM Ben via VHFcontesting <
vhfcontesting@contesting.com> wrote:
> Great info. Like to add my 2c.
> As mentioned, partial body irradiation must be included since it has been
> shown that some parts of the human body (e.g., eyes, testicles)
> may be harmed if exposed to incident radiation levels significantly in
> excess of the recommended levels. Think about carrying a cellphone in the
> pocket when you have bad coverage and the phone goes to max power. Distance
> is an important factor, consider the 1/R² factor in the power density
> calculations (valid in the far field, near field more complex).
> For US, incident electromagnetic energy of frequencies from 10 MHz to 100
> GHz, the radiation protection guide is 10 mW/cm².
> (milliwatt per square centimeter) as averaged over any possible 6 min
> period. Please note that the 10 mW/cm² US standard is expressed in mW/cm²
> which is equivalent to 100W/m². Canada and Europe are generally using a
> more conservative standard of 10W/m², i.e. 10 times lower than the US
> standard. Go figure!
>
> As an example, the Radiation Protection Bureau of Health Canada has issued
> a series of safety codes. Canada's Safety Code 6 is titled
> “Limits of Human Exposure to Radiofrequency Electromagnetic Energy in the
> Frequency Range from 3 kHz to 300 GHz.”
> The official document number is HC Pub:091029. See:
> http://rfsafetysolutions.com/RF%20Radiation%20Pages/Safety_Code_6.html
>
> Exposure Limits for Uncontrolled Environments
> Frequency Electric Field Power Density
> (MHz) (V/m) (W/m²)
> 0.003–1.0 280
> 1.0–10.0 280/f
> 10–300 28 2
> 300–1,500 f/150
> 1,500–15,000 10
> 15,000–150,000 10
> 150,000–300,000 6.67 x 10-5f
>
> Interesting to note that the standard for frequencies predominally used
> for ham communication, 10-300 MHz, actually have a
> lower PD standard of 2 W/m². I believe this is due to the fact that the
> body or bod parts can act like a loaded dipole resonating at those
> frequencies. It is important to be aware of the radiation hazard and take
> proper precaution. Final note, with the
> introduction of the new 5G wireless standard, we will all be exposed to
> more RF radiation due to the large number of microcells, even flying in
> LEO,
> that will be used.
>
> 73 de AB4AB
> Ben
>
> -----Original Message-----
> From: Steve(K1IIG) <stephen.tripp@snet.net>
> To: James Heck <jamesvheck@gmail.com>
> Cc: pnwvhfs <pnwvhfs@googlegroups.com>; Vhf Contesting Vhf Contesting <
> vhfcontesting@contesting.com>
> Sent: Wed, Mar 20, 2019 5:09 pm
> Subject: Re: [VHFcontesting] Microwave Energy Directed at Overseas
> Personnel?
>
> Thanks Jim for you better description of non-ionizing vs ionizing
> radiation. Seems to me us v/u and uv hams should be aware of all this. I
> plead guilty to not paying attention when bench testing transmitters all
> the way
> to 10ghz.
> 73's
> Steve HF-10ghz
>
>
> Greetings to All,
> Perhaps something should be said about "radiation". It comes in two kinds
> : ionizing and non-ionizing. Their difference has to do with the wavelength
> of the signal and what those signals do to our bodies when they strike us.
>
>
> Ionizing energy causes electrons to be stripped from the atoms they
> strike. That destroys our tissue and organs. We call it radiation
> poisoning, and it will indeed kill you as it did to many people living in
> Nagasaki and Hiroshima , Japan. The sun and nuclear explosions are sources
> of ionizing energy.
>
>
> Non-ionizing energy does not strip electrons off the atoms in our body. It
> does however cause those atoms [and cells] to vibrate back and forth
> rapidly. As the cells vibrate they take energy from the signal. This causes
> the cells and tissues of our body to heat. If the cell over heat they are
> damaged...…..or it could be said we are "cooked". Microwave ovens use this
> vibration phenomime to heat food.
>
>
> Not being cooked is controlled by a number of factors. Here are the most
> important:
>
>
> 1 If our body is small compared to the wavelength of the signal's energy,
> it will not absorb much of the signal.
>
> 2. Your body has a blood circulatory system which will carry the heat to
> your outer skin surface and lungs where it is conducted out or off of the
> body. Therefore, little or no damage results. You will sense "heat" if you
> are being exposed to a signal level your body is having trouble cooling
> down from Eyes, which have little blood circulation, are the most easily
> damaged organ of our body from the heating situation. And thus the old
> saying "never look down a waveguide" is still true today.
>
>
> Therefore, we can conclude that the danger to the human body from
> non-ionizing radiation sources exists when the signal wavelength compares
> to or is smaller than our bodies. That would be signals in the VHF, UHF,
> and microwave wavelengths/frequencies.
>
>
> OSHA has established required maximum radiation levels standards for
> people working in both ionizing and non-ionizing areas. People working
> around large active microwave antennas or on broadcast towers, which have
> FM and television installations, need to pay close attention to OSHA
> standards which are intended to keep them from harm.
>
>
> Recovery from radiation energy injuries is a slow process without happy
> outcomes guaranteed. The reason is that the radiation damage tends to go
> deep into our tissues and organs. Our bodies will have a rather serious up
> hill climb to recovery the function of those important organs.
>
>
> Regards to All
> Jim Heck, W7JVH
> retired director of engineering of radio HCJB-Ecuador, S.A.
>
>
>
> Virus-free. www.avg.com
>
>
>
> On Tue, Mar 19, 2019 at 6:19 AM Steve(K1IIG) <stephen.tripp@snet.net>
> wrote:
>
> I too saw that show and question why they did not have RF detector
> devices
> if they suspect China or Russia was using Hi Pwr RF causing health
> issues.
> They spoke about the possibilities that the same freq as Microwave ovens
> (2ghz) being used.
> If the RF was so intense a simple microwave oven detector would have
> picked
> up the signal. I happen to have one of these devices used to detect
> leakage
> from a microwave oven. When I was a cellular tech we were issued Narda
> RF
> detector badges. When
> the techs were exposed to hi RF fields the Narda would warn us at 50%
> unsafe
> levels. When I was on a bank building in Springfield MA the alarm would
> always go off if I stayed on the roof near the antennas. The roof top
> was
> loaded with hi power
> pagers and cell antennas. If I stayed for any length I would get a nasty
> headache. The headache would not last when I left the roof top and I was
> told RF exposure did not stay in your body once out of the field. I can
> not
> think of the technical term for this. Cell companies must do an RF
> Density
> test at various distances and of course always passed this test. At one
> time
> early in the cell business we had to shut down the site or a particular
> face
> when climbers were on the tower. I do not believe this is today's
> standard
> practice.
> I have no clue if there are any long term health affects but for sure
> being
> exposed to high power can give you a headache.
> Steve
> K1IIG
> Cell tech/engineer 1984-2001
>
> > A “60 Minutes” story on 17march19 discussed various physical (cranial)
> > maladies experienced by USA government employees & their families,
> > POSSIBLY inspired by microwave RF energy directed at their residences
> or
> > offices. No mention was made of any RF field strength measurements!
> > Does anyone have ‘educated/learned’ comments on this report?? I have a
> few
> > empiric thoughts
> > on this, but am definitely not an expert.
> >
> > Bt73
> > Pete, n6ze: with qrp on 70, 33, & 23 cm bands
> > Sent from my iPhone
> > _______________________________________________
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> > VHFcontesting@contesting.com
> > http://lists.contesting.com/mailman/listinfo/vhfcontesting
> >
>
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