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As far as nobody really reacted to the statement of yours that passive =
ground screen under elevated radials is a mistake I would like to =
emphasize that it is not. Most of the comments in this thread would also =
lead you to a conclusion that by having a vertical elevated some 10 feet =
off the ground and using a few elevated radials leaves you hardly =
exposed to your ground conductivity.
Thus how can you deny that installing a nearly perfect ground screen =
under elevated vertical with a few radials frees you from 3-4-5-6 or =
whatever DBs of ground loss in the system?
Why not use ground mounted vertical then? Why have all the trouble with =
elevating?
4 Reasons for using 1 elevated radial:
1. You can tune the vertical by simply changing the radial length.
2. You can get some directivity in the desired direction (use 2 or more =
if you don't want that to cancel the currents!!)
3. You get different and better pattern from ground mounted vertical! 10 =
feet elevation on 80m gives you much better pattern especially F/B-wise =
on higher angles! Model if you don't believe!
4. You can get some horizontal radiation using 1 radial and elevating by =
more than 0.05 wl - you might want it for local presence!
I am using full size 80m 4Square elevated 10 feet with 1 elevated radial =
per vertical and a passive ground screen of 64 c.a. 1/4 wl radials per =
vertical on the ground - it's my ideal system! In the air tests have =
given only very good results too.
I tried 4 elevated radials instead of one - did not perform better! =
Rather worse patternwise and modelling confirms that.
I tried to connect the ground screen to the vertical - no change except =
in the resonance curve as expected!
I had somebody also telling me that a traditional ground mounted system =
would give me much better performance!!!
Better kill that myth right now.
:)
73
Tonno
ES5TV
----- Original Message -----=20
From: K4IA@aol.com=20
To: K4BEV@aol.com=20
Cc: towertalk@contesting.com=20
Sent: Thursday, March 07, 2002 3:42 PM
Subject: Re: [Towertalk] Grounding an Elevated vertical
With all due respect to those who have suggested you create a ground =
screen in addition to the elevated radials, I think that is a mistake.
Your elevated radials are your RF ground and make up the second half =
of the antenna. If you add another RF ground 10 feet below I think you =
will throw the antenna off without gaining anything. For one, the 10 =
feet of wire to the earth will act as part of your antenna system. =
Elevated radials require fewer radial wires and work just fine. They =
don't need any help. If you feel compelled to improve your=20
RF ground add 2 more elevated radials. Cebik seems to think 4-8 =
elevated radials slightly less than 1/4 wavelength long is all you need. =
Check out his articles at http://www.cebik.com/gp.html and =
http://www.cebik.com/gup27.html
You do need a lightning ground and that is where your idea makes =
sense. Run a #4 wire to the ground rod and wrap the antenna end of it =
with electrical tape. Then tape the taped end to the bottom of your =
vertical. You could try to create your own spark gap by leaving some of =
the #4 exposed and have it close to, but not touching the vertical. Run =
your coax down the side of the ground wire and tape it to the ground =
wire for a foot or so before you take a right angle turn to run off to =
the shack. The theory here is the lightning, looking for the shortest =
and straightest path to ground, will jump across the electrical tape (or =
the gap) and go straight to ground. Nothing in the amateur realm will =
give complete protection against a direct strike but it may bleed off a =
lot of the hit before it travels back to your house.
The topic of grounding is a a **hot** one and this post may generate =
some strong comments. That is good. I don't think my idea will hurt =
anything and if you want to try attaching the radials to the ground =
wire, you do that to as an experiment. Let us know how it turns out.
Radio K4IA
Craig Buck
Fredericksburg, Virginia USA
QRP ARCI #2550 FISTS #6702 CC 788 Diamond #64
K1 #470 K2 #2460=20
----------------------------------------------
For cheap long distance, 800#s and more
Tune to http://www.ld.net/?bucksavers
4.9 cents/min - no monthly fees=20
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<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>As far as nobody really reacted to =
the=20
statement of yours that passive ground screen under elevated =
radials is a=20
mistake I would like to emphasize that it is not. Most of the =
comments in=20
this thread would also lead you to a conclusion that by having a =
vertical=20
elevated some 10 feet off the ground and using a few elevated radials =
leaves you=20
hardly exposed to your ground conductivity.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thus how can you deny that installing a =
nearly=20
perfect ground screen under elevated vertical with a few radials frees =
you from=20
3-4-5-6 or whatever DBs of ground loss in the system?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Why not use ground mounted vertical =
then? Why have=20
all the trouble with elevating?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>4 Reasons for using 1 elevated=20
radial:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>1. You can tune the vertical by simply =
changing the=20
radial length.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>2. You can get some directivity in the =
desired=20
direction (use 2 or more if you don't want that to cancel the=20
currents!!)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>3. You get different and better pattern =
from ground=20
mounted vertical! 10 feet elevation on 80m gives you much better pattern =
especially F/B-wise on higher angles! Model if you don't =
believe!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>4. You can get some horizontal =
radiation using 1=20
radial and elevating by more than 0.05 wl - you might want it for local=20
presence!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I am using full size 80m 4Square =
elevated 10 feet=20
with 1 elevated radial per vertical and a passive ground screen of 64 =
c.a. 1/4=20
wl radials per vertical on the ground - it's my ideal system! In the air =
tests=20
have given only very good results too.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I tried 4 elevated radials instead of =
one - did not=20
perform better! Rather worse patternwise and modelling confirms=20
that.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I tried to connect the ground screen to =
the=20
vertical - no change except in the resonance curve as=20
expected!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I had somebody also telling me that a =
traditional=20
ground mounted system would give me much better =
performance!!!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Better kill that myth right =
now.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>:)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>73</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Tonno</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>ES5TV</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3DK4IA@aol.com href=3D"mailto:K4IA@aol.com";>K4IA@aol.com</A> =
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A title=3DK4BEV@aol.com=20
href=3D"mailto:K4BEV@aol.com";>K4BEV@aol.com</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Cc:</B> <A =
title=3Dtowertalk@contesting.com=20
href=3D"mailto:towertalk@contesting.com";>towertalk@contesting.com</A> =
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, March 07, 2002 =
3:42=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: [Towertalk] =
Grounding an=20
Elevated vertical</DIV>
<DIV><BR></DIV><FONT face=3Darial,helvetica><FONT size=3D2>With all =
due respect to=20
those who have suggested you create a ground screen in addition to the =
elevated radials, I think that is a mistake.<BR><BR>Your elevated =
radials are=20
your RF ground and make up the second half of the antenna. If =
you add=20
another RF ground 10 feet below I think you will throw the antenna off =
without=20
gaining anything. For one, the 10 feet of wire to the earth will =
act as=20
part of your antenna system. Elevated radials require fewer =
radial wires=20
and work just fine. They don't need any help. If you feel=20
compelled to improve your <BR>RF ground add 2 more elevated radials. =
Cebik=20
seems to think 4-8 elevated radials slightly less than 1/4 wavelength =
long is=20
all you need. Check out his articles at <A=20
href=3D"http://www.cebik.com/gp.html";>http://www.cebik.com/gp.html</A> =
and <A=20
=
href=3D"http://www.cebik.com/gup27.html";>http://www.cebik.com/gup27.html<=
/A><BR><BR>You=20
do need a lightning ground and that is where your idea makes =
sense. Run=20
a #4 wire to the ground rod and wrap the antenna end of it with =
electrical=20
tape. Then tape the taped end to the bottom of your =
vertical. You=20
could try to create your own spark gap by leaving some of the #4 =
exposed and=20
have it close to, but not touching the vertical. Run your coax =
down the=20
side of the ground wire and tape it to the ground wire for a foot or =
so before=20
you take a right angle turn to run off to the shack. The theory =
here is=20
the lightning, looking for the shortest and straightest path to =
ground, will=20
jump across the electrical tape (or the gap) and go straight to =
ground. =20
Nothing in the amateur realm will give complete protection against a =
direct=20
strike but it may bleed off a lot of the hit before it travels back to =
your=20
house.<BR><BR>The topic of grounding is a a **hot** one and this post =
may=20
generate some strong comments. That is good. I don't think =
my idea=20
will hurt anything and if you want to try attaching the radials to the =
ground=20
wire, you do that to as an experiment. Let us know how it turns=20
out.<BR><BR>Radio K4IA<BR>Craig Buck<BR>Fredericksburg, Virginia =
USA<BR>QRP=20
ARCI #2550 FISTS #6702 CC 788 Diamond #64<BR>K1 =
#470 =20
K2 #2460 <BR>----------------------------------------------<BR>For =
cheap long=20
distance, 800#s and more<BR><BR>Tune to <A=20
=
href=3D"http://www.ld.net/?bucksavers";>http://www.ld.net/?bucksavers</A><=
BR>4.9=20
cents/min - no monthly fees</FONT> </FONT></BLOCKQUOTE></BODY></HTML>
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