[TowerTalk] JAMAICA Antenna Question

[David Jordan]

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 at thepoint.net>
To: "David Jordan" <wa3gin at comcast.net>
Cc: <TOWERTALK at 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 at 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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