Ed,
What kind of noise dominates your noise floor on 40 meters. Are you limited
by power line noise or other man made noise (light dimmers, TV horizontal
sweep noise, computer hash), or a you mainly hearing skywave noise (white hiss
and thunderstorm crashes)? Your test data suggests a 3 S unit S/N difference
of between two omindirectional antennas under both daytime and nightime
band conditions? That doesn't seem physically possible unless you have some
kind of range effects (power line coupling that favors one antenna over the
other), or a near field noise source that due to proximity couples into one
antenna better than the other.
Mike, W4EF............................
----- Original Message -----
From: "N5NUG" <n5nug@ix.netcom.com>
To: <W8JI@contesting.com>
Cc: <towertalk@contesting.com>
Sent: Monday, January 22, 2001 8:43 PM
Subject: Re: [TowerTalk] precipitation static & folded verticals
> Hello Tom:
>
> Thanks for your input. Yes, the original question was about
> precipitation static. I have never had much of a problem with
> precipitation static. Only a lightning strike once about 6 years
> ago. If I changed the topic of discussion I apologize. I keyed in on
> the reference to noise in general. We don't get much snow in Dallas,
> only ice.
>
> Both of the verticals were at DC ground potential unlike yours. The
> impedance measurements were taken to get a relative likeness between
> the antennas due to the closeness to all the utility infrastructure
> and house wiring in the near field of both antennas. My QTH is a
> typical city lot for a low band antenna. You might as well toss out
> all the text book standards when trying to take local noise
> measurements in this environment with a vertical antenna that
> listens well in all directions.
>
> You are lucky you can see the interaction between your antenna
> 500'-600' from a tower at your location. There are not any towers
> around here, only half a dozen power line poles with ground wires
> running down to a earth ground. I would believe both antennas couple
> to these structures in a like manner in the space they are located.
> Not much choice for me in this environment. I would think enough
> noise to create a receive problem is probably ground wave anyway.
>
> I was talking about noise in general. I provided what I thought was
> a comparison between two antennas in a similar environment. One
> folded and one not. My antenna farm is very restricted for low band
> operation. I would think noise is noise in the near field and 5 to 6
> wave lengths on 40m would be about 800'. I bet that in my corrupted
> environment the noise would be pretty much uniform for both antennas
> at 75 feet apart from any or all directions. I don't believe you
> would see much difference in the local noise between the two
> antennas with only 75' separation on this lot for a single vertical
> antenna. 73, Ed - N5NUG
>
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