[Towertalk] NVIS antenna--reflector addition

[Guy Olinger, K2AV]

Noticed in the 2 element below, I didn't specify which wire was fed.
The 47.7 wire takes the power. The 7.4 wire is reflector only.

----- Original Message -----
From: "Guy Olinger, K2AV" <k2av@contesting.com>
To: "Al Williams" <alwilliams@olywa.net>; <towertalk@contesting.com>
Cc: <ead@arrl.org>
Sent: Wednesday, June 05, 2002 10:36 PM
Subject: Re: [Towertalk] NVIS antenna--reflector addition


> The ground is a reflector, but it is a lossy reflector.
>
> Best 75 degree numbers I can get for a dipole using earth as
reflector
> are around 6 or 7 dbi.
>
> I'm not sure what figures you were using for an NVIS antenna, but
try
> this out (7.025 MHz)
>
> Upper wire = 67.5 feet long, 47.7 feet high
> Lower wire = 68.4 feet long, 7.4 feet high
>
> I get 11 dbi at 75 degrees with 11.4 dbi straight up.
>
> The maximum NVIS signal I can get for a single wire = 67.3 feet
long,
> 14.3 feet high. which is just under 8 dbi straight up.
>
> That's 3 1/2 db extra signal from the reflector, unless you consider
> 3.5 db superfluous.
>
> And I suspect you didn't have the program which would search out the
> maximum for the single wire NVIS
>
> The two wire is a very doable 40 meter NVIS antenna.
>
> 73, Guy.
>
> ----- Original Message -----
> From: "Al Williams" <alwilliams@olywa.net>
> To: <towertalk@contesting.com>
> Cc: <ead@arrl.org>
> Sent: Wednesday, June 05, 2002 1:33 PM
> Subject: [Towertalk] NVIS antenna--reflector addition
>
>
> > Our club is planning to have an NVIS antenna for 80m
> > and 40 meters during Field Day.  However:
> >
> > The World Radio Books publisher's "Near Vertical Incidence
> > Skywave Communication" book purchased from ARRL
> > contains two articles (by the same author) showing an
> > NVIS wire reflector added to the driven NVIS wire element.
> >
> > Because the ground itself is a reflector, and because
> > EZNEC confirms that adding the reflector is superfluos,
> > we do not think a reflector will help.
> >
> > Agree?
> >
> > k7puc
> >
> >
> > _______________________________________________
> > Towertalk mailing list
> > Towertalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
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