Subject:  Re free zones - more on satellites, ETC. (fwd)
Date:     Fri, 13 Feb 1998 203815 -0600 (CST)
From:     "Roy L. Beavers" <rbeavers@llion.org>
To:       emfguru@hotmail.com
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---------- Forwarded message ----------
Date: Sat, 14 Feb 1998 12:31:17 +1100
From: Stewart Fist 
To: "Roy L. Beavers" 
Subject: Re: free zones - more on satellites, ETC. (fwd)

Quite frankly, I just don't understand a lot of the stuff in Bertha
Dumpe's posting.

Newton's law about action and reaction being equal and opposite have
nothing to do with philosophy or radio waves, but with the physical motion
of objects subject to intertia, and therefore having mass.

There is no Newton's law applied to R/F from space.

>But when a cellphone signal must transceive from space, airwave resistance
(phone to 
> satellite) or gravitational pull mandates that the cellphone signal be
more powerful.

The need for more power to reach out into space from a satellite handset
has nothing to do with airwave resistance, it is the operations of the
inverse square law over distance, and also related to the size of the
receiving antenna (in satellites it can be a collecting dish, since the
source is always close to alignment down the boresight).

Receiving signals from a satellite is actually very low power because the
satellite is only transmitting from solar cells, using a dish to focus on
a narrow 'cell' on earth, and is up against a very low radiation
background of the stars.  The downpath signal from satellites is
extraordinarly low in power.

The reason why high frequencies in the 27GHz region is used is because
these are line-of-sight transmission.  For terrestrial use, you need to be
able to see the transmitter, and that is difficult in tree-lined streets,
and at ground level with hills (which is why it is only now coming into
use for short-range 'local' LMDS television).

Satellites use super high frequency because a) it was unused by
terrestrial transmissions and therefore had b) low level of background and
interference and c) there is plenty off it.  Each time we go up a band in
the radio spectrum we gain 9-times the amount of spectrum we had in total,
before.

>Toroidal antenna .... Thereby, such an antenna will carry signals to ships at
>and under the sea as well as satellites and handheld phones. 

The design of 'toroidal' antenna does nothing to reach under the sea,
unless there is some new development that I haven't heard about.  Reaching
submarines depends on the ability of radio waves to penetrate water, and
most of the frequencies that we currently use go no further into saline
solutions than a few inches at most.  

However the really low frequencies, given enormous power, can encircle
the globe (because their wavelength is proportional to the global
dimensions) and can penetrate water.  This is a product of extreme
wavelength and extreme power, not antenna design of the type being
discussed above.  However, to transmit such low-frequency signals requires
enormously long antenna installations on masts, with wire strung between
(usually measured in terms of miles) because antenna length and wavelength
(frequency) are mathematically linked. 

Which is why the US Navy only has three or four transmitters around the
world that can do this, and then only for very low-rate text.  In
Australia, our contribution is a so-called secret base, in a remote
locations at North West Cape in Western Australia

> Cellphone users have already developed brain tumors from 1.5 GHz (now
2.5 GHz) phones. 
> Wait till they start enjoying the lovely 29 GHzphones. Cancer will
develop over a
> short period of usage.

Cellphones implicated in possible brain tumours have been operating in
the 800 to 900MHz range. The simple reason (we suspect) may be that the
higher frequencies (PCS) haven't been used long enough to create problems.
At least, that is what most activists suspect, and it is a legitmate worry
— but it is by no means a certainty.

To my knowledge, there is only a slight suspicion that higher GHz
wavelengths of PCS will prove to be more dangerous than the lower MHz
(cellphones), and this could well be offset by the fact that at higher
wavelengths the phones will output less power because they transmit over
lesser distances, but this may be offset by people using them more.  

However there is certainly no suggestion that the potential health
effects of R/F will rise in a linear fashion with frequency to the limit
of the radio spectrum — where every step up in the frequency increases the
dangers.  It could well be that higher frequencies are less dangerous.

If this invariable equation of frequency with danger were so, then the
logic is that at the highest possible 'radio' frequencies (which is
infrared light at the margin -- and then into visible light) would be the
most dangerous.  There's no evidence of this whatsoever, although higher
still (UV) does appear to produce melanomas.

I would have concerns about satellite handset (as distinct from space
segment) power, but only because of its likely need for a high pulsed
output in a device used close to the body.  Frequency may play a part, but
at present we don't know.

-- 
Stewart Fist - technical writer and columnist
See: http://www.australian.aust.com/computer/cmpcols.htm
       http://www.abc.net.au/http/sfist/      (some archives)
       http://www.electric-words.com           (main archives)



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Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html