David,
Thanks for sharing the study.
I am trying to digest it. Need to go through it again.
He says: " There is an optimal height for an elevated groundplane,
that height is not at ground zero, and is typically around 0.05
wavelength. (The statement the higher-the-better is not always true for
such systems.) "
This figures to a little over 15 feet above ground for 160M. I can
manage that.
I think he has another study for the added efficiency with a ground
screen under elevated radials.
I want to find that one too.
Bob
K6UJ
On 11/9/16 9:04 AM, David Cutter wrote:
Hello Peter
I haven't done any work on this, but Ralph has. Have a look at this
site and others of his:
http://www.arising.com.au/people/holland/ralph/shortvert.htm
David
G3UNA
----- Original Message ----- From: "Peter Voelpel" <dj7ww@t-online.de>
To: <topband@contesting.com>
Sent: Wednesday, November 09, 2016 4:57 PM
Subject: Re: Topband: 160 m inverted L
Think of a dipole close to the ground, it will not be efficient with all
that coupling to earth and resulting losses.
73
Peter
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of David
Cutter
Sent: Mittwoch, 9. November 2016 17:37
To: Mike Waters; Rob Atkinson; topband
Subject: Re: Topband: 160 m inverted L
I recall reading from Ralph Holland that 0.015 wavelength was a good
height.
David
G3UNA
----- Original Message ----- From: "Mike Waters" <mikewate@gmail.com>
To: "Rob Atkinson" <ranchorobbo@gmail.com>; "topband"
<topband@contesting.com>
Sent: Wednesday, November 09, 2016 4:11 PM
Subject: Re: Topband: 160 m inverted L
Fifty feet?! That means the feedpoint --the bottom of the antenna--
would
be 50 feet up! Do you know how high the top would have to be? I don't
agree
with that at all. And I've never heard of anyone who ever did that.
The four elevated radials in these tests were just 16 feet high! And
what
is more, the frequencies were 1490, 1450, 1240, and (maybe) 625 KHz.
Almost
as effective as 120 buried radials.
lists.contesting.com/_topband/2007-11/msg00248.html
I forget the radial height in Rudy Severns' (N6LF) tests, but IIRC they
weren't anywhere near 50' high.
My two elevated radials were 10' high. I know that a little higher
(and a
few more of them) would have been better, but I can tell you that that
160m
inverted-L WORKED! And I'm by no means the only one. :-)
73, Mike
www.w0btu.com
On Wed, Nov 9, 2016 at 6:10 AM, Rob Atkinson <ranchorobbo@gmail.com>
wrote:
The rule of thumb for effective elevated radial height is 1/10
wavelength,
so on 160, around 50 feet up.
73
Rob
K5UJ
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