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From: Dave Holford
X-Mailer: Mozilla 4.7 [en] (Win95; I)
Subject: Re: Any ideas on measuring radiation in the home ?
References: <%_wk9.52964$1C2.firstname.lastname@example.org> <3D9442F1.42F2FBAF@webaccess.net> <3D9467AC.9745AC66@webaccess.net> <8a%k9.56338$1C2.email@example.com>
Date: Sat, 05 Oct 2002 12:05:23 -0400
NNTP-Posting-Date: Sat, 05 Oct 2002 12:04:43 EDT
Organization: Bell Sympatico
> I did some surveying around the house :
> I find that the recessed ceiling lights and HVAC sheet metal ducting
> inlets/outlets show directed antenna patterns - single lobe, two lobes,
> etc - when circled by an AM radio receiver (there is a null when you point
> the radio antenna directly at it). This may indicate some radio interference
> coming from them.
> Also, the walls seem to be showing grainy noise (the signal is completely
> overwhelmed by the noise) in certain well defined regions - eg : one
> straight line along a bedroom wall at 2 feet height; both sides of the
> toilet tank in one bathroom; one side of the toilet wall; a diamond shaped
> region over the towel rack that extends up and down along a straight line;
> one corner of the kitchen stand showed really strong interference; one
> vertical line along the living room center wall; the fire-sprinkler pipe in
> the basement; the mains switch box showed strong noise, etc.
> The reception in the home general area itself seems to be directional with
> twin lobes in the horizontal and vertical directions (this must be as
Did you really not expect metal objects and wires to modify the
radiation patterns/signal strength levels of electromagnetic radiation?
It's simply amazing the effects of house power, telephone, video,
plumbing, HVAC etc. can have on radio signals. And, if you are one of
those lucky? people with metallic foil backed insulation things get even
more interesting. A basic understanding of electromagnetic principles
will help your paranoia. The effects can be even more amazing if the
joints, i.e. in the HVAC, are corroded.
I used to use a coffee can and a piece of aluminum foil to demonstrate
this sort of thing when I taught Ham radio courses.
One of the best personal demonstrations I have ever seen was placing the
TV antenna under a carpet and watching how the signal changed as people,
and even the cat, moved around. (Yes you used to be able to purchase
flat TV antennas to put under the carpet, but I made my own).
Parking a car near the end of an outdoor antenna can also have amazing
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