I understand the notion of the physical response patterns
of verticals and horizontals. And, I would agree with Jim lux's
observation about groundwave absorption.... except for the
question of how rapidly it falls off, and whether in the
relative near field (10 wavelengths or so from the antenna) that
absorption is sufficient to attenuate the horizontally polarized
noise signal.
K8RI's comments which triggered my question reflect his observation
that his vertical is very quiet. I'm wondering how much of our
perception of noise propagation is due to failure to properly
decouple our feedlines...and is common mode pickup. (again,
refer to w1his's paper.)
My R7000, which is a 3/8 wave unbalanced vertical, with a 4:1 balun
at its feedpoint and decoupling chokes....is extremely noisy in
my present location. Adding decoupling a'la Counselman, w1his,
reduced this noise 6 or 7 S units.
My 80m carolina windom...an off center fed and therefore unbalanced
antenna--installed horizontally--was equally noisy. Adding common
mode chokes, per w1his instructions, reduced this noise 6-7 S units.
I can't say that one antenna is quieter than the other, at the moment,
leading me to believe that I STILL have some common mode pickup, or
possibly that the noise power is radiated equally in both polarities.
The number of variables in any situation is usually a problem, and
attacking the discussion in a general way gives us a huge number of
variables. Which brings me back to the original question.
How do we know what the polarity is....or is it simply a complex mix
based on the source and the sources proximity to a vertical ground wire?
Further away, more current flows in the horizontal wire, before finding
a ground run.
n2ea
-----Original Message-----
From: Bill Turner [mailto:dezrat@copper.net]
Sent: Sunday, November 12, 2006 10:09 AM
To: Jim Lux
Cc: Jim Jarvis; towertalk@contesting.com
Subject: Re: [TowerTalk] vertical vs horizontal--a different take
Exactly. And the corollary is that DX signals, coming down from the
ionosphere, do not suffer this horizontal attenuation. This is why a
horizontally polarized antenna receive skywave signals just fine but
receives very little locally generated groundwave.
This is what leads to hams saying a vertical is "noisier" or a
horizontal is "quieter", but technically that isn't really true. The
real difference is the amount of noise that reaches the antenna in the
first place, not whether the antenna "picks it up" or not.
Bill, W6WRT
------------ ORIGINAL MESSAGE ------------
On Sun, 12 Nov 2006 06:47:24 -0800, Jim Lux <jimlux@earthlink.net>
wrote:
>It's not that the noise source is H or V pol, it's that for
>ground/surface wave propagation, H pol is strongly attenuated, so
>that by the time it gets to your antenna, it's all V pol.
>
>Jim
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