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Author Topic: random wire antenna  (Read 8605 times)
N8REF
Member

Posts: 1




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« on: June 17, 2000, 05:52:13 PM »

Would like to use a copper random wire    antenna and wonder about radiation hazard to birds and other wild life.   Would limit running to 100 watts.The alternative is putting the wire in the attic and then worry about fire. Visible antennas are not permitted where we live.   Thanx for any opinions.   cday@excite.com
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K1TWH
Member

Posts: 115




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« Reply #1 on: June 17, 2000, 06:52:18 PM »

N8REF,
      At 100 watts I'd use insulated copper wire (but
not because of birds which are tiny when compared to
the size of the wave on shortwave).  I've never had
a problem with wildlife or trees using 50-100 watts
output.  For wire antennas in the trees outdoors I've
used #26 insulated wire (from 'The Radio Works') and
the wire is very hard to see up in the air.
      If you need to place antennas in the attic,
again use insulated wire, only now you can use #14 wire
without worrying about it being seen.  Keep about 3"
between the wire and other objects.  You should review
the RF Exposure limits according to how much space there
is between your antenna and people.  Often power on
10-12-15 meters is limited, but by 80M the 100W is
usually OK.  
       73,  Tom Howey  WB1FPA  'howeys@compuserve.com'
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WB6BYU
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Posts: 17064




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« Reply #2 on: June 21, 2000, 11:37:29 AM »

You can use amazingly thin wire for an antenna, even at
100 watts.  A practical limitation is around #32, because the
birds can't see it in time to avoid it.  In general, an outside
antenna will probably generate lower exposure levels than
one in the attic (because it will be further from people.)

(I remember the story of someone who put up an invisible antenna
using #28 copperweld wire.  A few months later the apartment
manager asked him about his antenna.  It didn't bother him, but
it had upset one of the neighbors.  No, they couldn't see the
antenna wire, but they could see the birds sitting on it!)

I've also had good results tucking an insulated wire under the
shingles on my roof (choosing a matching insulation color) or
stapling it in a loop around the house under the eaves and feeding
it with balanced line or twisted pair.

At HF frequencies at least, the radiation exposure to birds and
other wild life should not be enough to worry about.

   Good luck!

     - Dale WB6BYU
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