I think the issue is not whether a vertical needs radials or not.
A vertical monopole needs a ground system or a counterpoise. The ground
system can be the actual ground or radials, or both, or even the shield of
the coax (and your station at the end of it). If you have a good ground and
it is connected via a low impedance path, you may not need any radials. (I
don't use any at C6AGU, but the antenna stands in salt-water.) But if your
ground is poor, you do need radials, or some other effective counterpoise.
Every location is different and you should plan accordingly.
It is very simple to determine whether your ground system is adequate. Model
and measure your antenna. If the model indicates a feed point impedance of
25 Ohms and you measure 50 Ohms, the extra 25 Ohms is probably contributed
by the (poor) ground system. (Of course it could be a poor model too.)
73,
George,
AA7JV
On Sun, 16 Sep 2018 10:11:06 -0400 (EDT)
kolson@rcn.com wrote:
Well, my system here at K3OX is a "T" with a 40 ft vertical section and a 90 ft flat top. It sort of worked OK when I first put it up, but it works much more OK after about 32 random (to fit my 4 0 x 110 lot) radials were installed. It would work better yet if I had more and longer radials, and mo' better than that if the vertical section was 130 ft!
So saying an antenna "works" is a relative thing. But the moral is, you do what you can. T o paraphrase Clint Eastwood, "A man's gotta know his antenna limitations".
73 Kevin K3OX
----- Original Message -----
From: "Peter Voelpel" <dj7ww@t-online.de>
To: topband@contesting.com
Sent: Sunday, September 16, 2018 9:44:46 AM
Subject: Re: Topband: Use shunt fed tower
It can work and it does.
I used a shunt fed tower without radials for a couple of years on the former
qth just with the tower grounding.
Now I feed the tower directly and against a single sloping radial, it works
great and is also a better receiving antenna then my relatively short
beverages.
73
Peter, DJ7WW
-----Original Message----- From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of John
Harden, D.M.D.
Sent: Sonntag, 16. September 2018 02:43
To: daraymond@iowatelecom.net
Cc: topband@contesting.com; cfytech24x7
Subject: Re: Topband: Use shunt fed tower
A shunt fed tower requires radials period. It cannot work without them!
73,
John, W4NU
Sent from my iPhone
On Sep 15, 2018, at 1:55 PM, <daraymond@iowatelecom.net>
<daraymond@iowatelecom.net> wrote:
It makes no difference how the tower is fed, a vertical antenna must have
radials of some kind to be effective. 73. . .Dave, W0FLS
-----Original Message----- From: cfytech24x7
Sent: Saturday, September 15, 2018 11:29 AM
To: topband@contesting.com
Subject: Topband: Use shunt fed tower
A shunt fed tower is a vertical antenna so it offers lowest take off
angle. Shunt feeding avoids need for radial field. Any horizontal wire
antenna is going to put most of your radiated energy out at high angles,
unless you can get it at least a half wavelength of height. A loop may be a
quieter antenna for RX but your existing inverted Vs are no doubt better for
TX.
There is some art and experimentation involved in the matching but the
results will be worth the effort. I would start with your highest antenna
for top band, next highes for 80m. Note that your yagis will act nicely as
capacitive hats to add to effective tower hight.
Gl es 73, ab1vl chuck
Sent from my Galaxy TabR A
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