Hmmm, I think what I've read says it is in fact the "F2" layer that does
the work Don. Please check out your reference.
Also, any input to my specific question which has nothing to do with the
layer that produces the effect?
http://www.raynet-hf.net/tiki-download_file.php?fileId=30
73,
Dave
wa3gin
----- Original Message -----
From: <n8de@thepoint.net>
To: "David Jordan" <wa3gin@comcast.net>
Cc: <TOWERTALK@contesting.com>
Sent: Saturday, December 03, 2011 11:40 AM
Subject: Re: [TowerTalk] JAMAICA Antenna Question
Dave ...
I think the F2 layer and NVIS are not "compatible". NVIS usually
utilizes the "D" layer, IIRC.
73
Don
N8DE
Quoting David Jordan <wa3gin@comcast.net>:
> Hi Folks,
>
> Now that the F2 layer is producing some good refraction I've got a
> question about the NVIS Jamaica antenna.
>
> A few years ago I built this Jamaica antenna, basically four 1/2 wave
> wires or two full way dipoles fed in phase and spaced 1/2 wave apart.
>
> It was a cold day in winter when the antenna went up. I cut the wires to
> 70ft ea. and spaced the dipoles at 70ft. Used 600 ohm open wire for the
> phase line and drop to the coupler. It was easy to match on 40m. The
> wires are 18ft AGL.
>
> The antenna works as claimed when NVIS is supported by the F2 layer. Much
> better than a dipole at 50ft for stations within a few hundred miles.
> I've always wondered if it would be worth the effort to go back and
> prune the wires...
>
> The question is would performance of the antenna improve noticeably by
> pruning the elements to resonance on 40m?
>
> 73,
> Dave
> wa3gin
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