[TowerTalk] Definition of Ground Screen vs. Radials, Request for Information

[berferd]

Since I have a ground mounted multiband vertical (Butternut HF9V), I've
wondered if a large ground screen would minimize losses better than a set
of radials.

I currently use both.  I have 24 radials of various lengths and a 10x12' piece
of 1/4" ground fabric directly under the antenna (tacked down with garden
stakes so I can go right over it with the lawn mower).  Since the bandwidth
on 80 meters is pretty narrow (38 kHz), I'm confident that I have a fairly
efficient system.

But since the radials are there to prevent ground losses, wouldn't using
a larger ground screen (say, a 1000 sq. ft. piece of ground fabric) do
a better job?  Obviously the ground fabric is much more dense than
evenly spaced radials, so wouldn't it do a much better job of minimizing
ground losses?   If I were sure it would be a better way to go, I'd increase
the area of ground fabric, since the grass grows up through it and hides it
unless you look at the ground closely.

I'd also be interested in reading about anyone's experience with
ground screens vs. radials.

73,
Jeff
KI0RO


On Sun, 13 Aug 2000, Jan Ditzian wrote:
> I have been trying to follow the recent posts concerning ground screens and
> radials, but I would not take an oath that I could define the two terms.  I
> would appreciate some comment on my understanding of the terms, and perhaps a
> better set of definitions.
> 
> Radials
> I believe that the term "radials" implies wires that are attached to one side of
> the feedline at the point where the other side becomes the antenna, such as a
> bottom-fed vertical, adn fanning out in some way.  Therefore, I assume that a
> vertical dipole usually is not said to have radials, because they would cover
> half the antenna.  Radial length is a separate issue, and radials can be any
> length, with varying results.
> 
> Ground Screen
> A "ground screen" is a set of wires, beneath or somewhere near an antenna, not
> connected to either side of the feedline at the place where it becomes an
> antenna (I am really unsure of this definition).  These wires may be in any
> configuration (orientation), and of any length, and perhaps these two variables
> will be important in determining the effectiveness of the ground screen.  A
> dipole antenna installed near a vertical that has an effective set of ground
> radials may see those radials as a ground screen when the dipole is in use.
> 
> Counterpoise
> W8JI recently used the term "counterpoise," and I would define that as any
> conductor connected to one side of the feedline, whether the conductor be
> radials, a single wire, a lump of metal, ground stakes, a tuned circuit and
> wire, or another antenna, at some point along the feedline to the "antenna" for
> which this conductor is supposed to serve as a counterpoise.
> 
> I assume that the function of these devices varies, depending on what is
> constructed and where it is placed.
> 
> Nomex e-mail program is ON.  Flame away, but remember, some Towertalkians may be
> under 21.
> 
> 73,
> Jan, KX2A
> 
> 
> --
> FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
> Submissions:              towertalk@contesting.com
> Administrative requests:  towertalk-REQUEST@contesting.com
> Problems:                 owner-towertalk@contesting.com

--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com