Some thoughts inserted in Dan's comments...***


"Dan Andersson" wrote in message
...
Thierry wrote:
...
My company has installed a Radar Tower for Port survaillence. The tower
is about 50 meter height on top of the of a 3 stories building roof and
my office building just below the tower on the same level, 20 meter away
from the tower. At the same time, the surrounding is my working area (
Jetty Terminal for ships loading and unloading activities ). I can say
that I'll be around that area 12 hours a day for another 20 years.
My question:
Is it safe to work in that area????
Thanks in advance
Thierry

So, what about Radar then...

First, There are two "kind" of RF radiation, non-ionizing and ionizing and
effects emanating from very high voltage nearby different materials.

*** Perhaps a typo, but the ionizing type is not a kind of RF
radiation. Ionizing radiation is nuclear radiation. This radiation is able
to strip electrons (and other particles) from atoms. RF does not do this as
we use it. It is unfortunate that we use the term "radiation" for both
things. In any case, it is not part of the original question.


Normally, non-ionising is to be more or less compared to sun light....

*** RF, Light is Electromagnetic radiation and produces, as far as we
know and can be proved, Heat.



As long as you are not overheating, there should be no harmful effects on
you. ...

*** Widely agreed, yet feared by many.


Now, radar radiation ...sometimes with stupidly high power....

** Not to the people USING it.



If you are standing near a RF radiating radar station, the average energy
is
what heats you up ...

*** Regardless of where/how you receive RF power, it produces a heating
effect. Standing in an open field, you are picking up RF from EVERY
transmitter within ear-shot (so to speak) and you have RF currents in your
body, but of course, the heat generated is infinitesimal. Tests have been
done to measure the low, yet measurable actual heating of things such as the
human face in the RF field of hand-held radio like power.


Some frequencies are really bad
for us because different parts of our bodies absorbs different amount of
energy on different frequencies.

*** The effect is that of heating and the most prominant effect is the
heating of the water content in things - us included. Water (H20) absorbs
RF best around 900 MHz and again around 2500 MHz. There may be more
frequencies, but these are the two used in microwave ovens (900 earlier and
2400 now - I believe). When it does absorbe it ( as opposed to reflecting
it, which it may do depending on how good the impedance match is) the water
heats. The old (possibly urban myth) story is of the radar techs up at the
old Dew Line Early warning radars would stand in fornt of the High power
radar antennas to warm up when working outside. The standard joke is that
they had small families after that...



Let's take a party example... Many key fobs, alarm buttons for car locks
etc, operates on 418MHz. It happens to be approximately where a normal
head
are resonating... Try walking just about out of range for your alarm/lock
button for your car, point the key fob against your head and press the
unlock key, voila, in most cases, you increase the range of the key
fob....
Dan / M0DFI

*** Mine is around 320 MHz. I seriously doubt that the head resonates
there, or has much of a resonance to speak of at any frequency. This
"range extending of the keyless remote" is easily duplicated by various
placements of your other hand, arm and other parts of the body, near the
remote. I play with it often walking across the parking lot to the car. It
can be best explained considering that being conductive, the body can pick
up RF from the fob and be an added part of the antenna in a
quasi-parasitic-element manner. The "antenna" in the fob is, at best, an
extremely poor one (not being anywhere near 1/4 or 1/2 a wavelength, nor
being a loaded antenna that is matched to the transmitter) and any help it
gets will frequently be observed as positive. This effect is very dependant
on things like polarization of the auto's receive antenna (if there is one
with a recognizable polarization), polarization of "you as an antenna",
direction (as the transmit pattern will most certainly be directional as
well as the receive pattern), and probably innumerable other complexities of
the RF environment you happened to be immersed in.

Any kind of a conductor can be brought close to the fob and have a similar
effect. I've done it with long screwdrivers and pieces of wire. Careful
placement of a half wave wire can achieve astounding range....comparatively
(to me, anyway, but then, there are those that say I am easily amused).
Nerd that I am, it's fun to see how much range you actually can get...just
for the bleep of it. I should get a life at times. (:-) Please no
agreement.

73, Steve, K,9.D'C;I

Oh yea...the origainsl Radar near the office question. Do a search on
something like the Russian radar illumination of the American Embassy. I
believe there are those that claim the Americans which the Russians were
radiating with Radar got irritable or some such symptom(s).

73

Steve,

Your assertion is simply not correct. You may be thinking of particle
radiation, such as electron (beta), neutron, proton, alpha, cosmic,
etc., but pure photon radiation can certainly be "ionizing". A
well-known example is ordinary medical x-rays. Ionizing photons would
not typically be called "RF", but there is no difference other than the
energy levels.

(I spent so much time in the early stages of my career dealing with
intense sources of ionizing radiation (photons) that I still glow in the
dark.)

Back to the original question, ordinary radar is clearly not "ionizing".
Not a good idea to be too close, due to possible thermal effects, but
otherwise no big deal.

73,
Gene
W4SZ

Steve Nosko wrote:
Some thoughts inserted in Dan's comments...***


"Dan Andersson" wrote in message
...


First, There are two "kind" of RF radiation, non-ionizing and ionizing and
effects emanating from very high voltage nearby different materials.


*** Perhaps a typo, but the ionizing type is not a kind of RF
radiation. Ionizing radiation is nuclear radiation. This radiation is able
to strip electrons (and other particles) from atoms. RF does not do this as
we use it. It is unfortunate that we use the term "radiation" for both
things. In any case, it is not part of the original question.

Gene Fuller wrote:
..., but pure photon radiation can certainly be "ionizing".

My ITT "Reference Data for Radio Engineers" says gamma rays
are EM waves which are certainly "ionizing".
--
73, Cecil http://www.qsl.net/w5dxp