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Re: [TowerTalk] Actual LP Performance vs Tribanders

To: "Peter Sundberg" <>
Subject: Re: [TowerTalk] Actual LP Performance vs Tribanders
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Mon, 28 Jun 2004 11:18:25 -0400
List-post: <>
Hi Peter,

> Just one comment regarding paragraph 2 where you say that
there is a
> 'filter' that often has more attenuation of horizontally
polarized signals
> than vertically polarized.
> I have found this to be totally the opposite. I do a lot
of EME and on both
> 144 and 432 MHz and with my systems (homebrew x-pol yagis
for 144 and a
> 28'dish with dual dipole feed for 432) I can instantly
switch polarization
> from horizontal to vertical.

Soil absorption is so bad at VHF that the earth looks pretty
poor for any polarization. As frequency is decreased from
VHF, the attenuation disparity between V and H polarized
signals rapidly increases.

Note the specific mention of **HF**.

> >3.) The most reliable way to measure gain or F/B of a
> >horizontally polarized HF antenna is with spacing in the
> >order of hundreds of feet, not thousands or more. The
> >"measure at a mile" stuff came right out of the thin air,
> >and became a myth. People actually think it is better
> >it is very much worse!

At HF and lower, the earth effectively short-circuits any
horizontal electric field. This is why Beverage antennas
work the way they do, and why local noise is predominately
vertically polarized at HF. Measuring a horizontally
polarized HF (or lower frequency) antenna at extended
distances is  certainly not a reliable or desirable test
method. It should be a SHORT distance in a clear area (on
all sides of the antennas), not a long one.

73 Tom


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