[time-nuts] frying pan antenna

Bob Camp lists at rtty.us
Tue Mar 16 16:13:48 UTC 2010


Hi

I have no idea what the ultimate source is, but in the houses I've been able
to directly "sample" a 20 db or more drop outside to inside is not unusual
from about 5 MHz right on up to GPS frequencies. Exactly what the frequency
dependence is I couldn't say. That's accompanied by a rise in noise from all
the stuff flying around on the power lines. Simply put indoors is not a good
place for an antenna. 

There will be magical frequencies and locations that won't make sense (up or
down in attenuation). I attribute that to all the metal running around.
Sometimes it helps, mostly it hurts. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Chuck Harris
Sent: Tuesday, March 16, 2010 10:03 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] frying pan antenna

There is a tremendous amount of signal degradation from
ordinary building materials.  I cannot get a lock at all inside
of my brick, with asphalt shingle house, but I get a quick
lock outside.

The tar paper isn't there as a waterproofing membrane, that
function is handled by the shingles themselves.  The tar paper
is installed by the framers, and provides temporary protection
while the house is waiting on the roofers to apply the shingles.

-Chuck Harris

Mike Naruta AA8K wrote:
> 
> Fascinating Bruce.  I had expected more degradation from
> the shingles.  The indoor antenna was a temporary set up
> until I could mount the outdoor one.  It works well
> enough that I use it as a back-up antenna.
> 
> I suppose an advantage to having an older home is the
> roof sheathing is composed of wooden boards, rather than
> the modern plywood with its bonding resins.
> 
> 
> Jim, you are correct about the fasteners.  This roof was
> stripped and redone two years ago.  There are the nails
> fastening the boards to the rafters, a layer of tarred
> paper, which for some reason roofers like to pierce with
> a liberal amount of staples, then the shingles nailed
> into place.
> 
> I had mounted a Sirius satellite radio antenna under
> the roof and discovered a position sensitivity.  I
> initially went with locations midway between the rafters,
> but discovered maximum signal level adjacent to a
> rafter.  I attribute this to the nailing pattern.
> 
> 
> This group is such an interesting resource.
> 
> 
> Mike - AA8K
> 
> 
> Bruce Griffiths wrote:
>> Below 600C the only significant source of microwave absorption in wood 
>> is the water content:
> 
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