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Old June 15th 05, 05:00 PM
 
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Telamon wrote:

"Is Your Coax Lead-In Actually An Antenna"
I posted about using coax for an antenna here a few days ago. If the
coax is not grounded on both ends it can be a very good antenna. I'm
using a 40 foot coax loop to listen to New Zealand as I type this. They
are S7 to S9 nice and quiet with no interfering noise with the volume
turned up. I live in town at the beach, other homes and businesses
where there is local noise generation aplenty all around me. Yes I also
have AM stations in town a few miles away.

Most voltage sensitive antennas I have put up get noisier the lower in
frequency I try to use them. The AM broadcast band is terrible on these
antennas around here. The coax loop is as quiet or better than the
ferrite loop in a portable.

For a loop this size you should use a shielded type where the shield is
split in the middle of the loop to minimize voltage pickup. You want
the antenna to be picking up the magnetic component of the EM wave
only.

--
Telamon
Ventura, California
--------------------------------------
I was addressing one's coax/feedline being an unintentional
antenna.
Triax is coax with an additonal outer shield that is insulated from
the inner shield.
See:http://bwccat.belden.com/ecat/jsp/In...d&P6=undefined

In the event line wrap kills this link, go to www.belden.com
and type triax in the search window.

I found the vertical wire leading up toy horizontal antenna was piking
up more noise then desired RF. I replaced it with coax but still had
some ingress. So I tried a piece of Triax. It removed all the noise one
the vertical
run.

Please see my post on "simple tests" to folllow.

Terry