How to get a good ground is very rocky terrian???
 

I live in S.E. Alaska on an island that is about 99% solid rock and i am
wondering what would be a good way to get an effective ground for my rig and
my antennas.
I have tried to drive a 4' ground rod in the ground and it will only go down
about a foot and a half till it hits solid rock.
I have considered just burying several strands of heavy bare copper wire and
using that for my ground.
Any sugjestions????
Thanks for any help any of you can give me.

EX WB8RSH soon to be KL7???

Mike

Forget about a ground rod. A single ground rod makes a very poor earth in
any sort of soil except salt water. It is no better than a shallow buried
radial wire of the same length.

You can have a good ground with a relatively small number of shallow buried
radial wires. Begin with 6 or 8 radials about 1/8th or 1/10th wavelengths
long. Then increase number until RECEIVED signal strength from several
stable transmissions stops increasing each time the number is increased by
50%.
----
Reg

"mike sebring" wrote in message
...
I live in S.E. Alaska on an island that is about 99% solid rock and i am
wondering what would be a good way to get an effective ground for my rig
and
my antennas.
I have tried to drive a 4' ground rod in the ground and it will only go
down
about a foot and a half till it hits solid rock.
I have considered just burying several strands of heavy bare copper wire
and
using that for my ground.
Any sugjestions????
Thanks for any help any of you can give me.

EX WB8RSH soon to be KL7???

Mike


Mike, don't even bother with burying anything then, use above ground
radials. Others here have run tests of various heights above ground, from on
it up to the antenna itself. Many seemed to work quite well if I recall.
Maybe someone in the group could model an idea of your available design. For
other applications you could also use a tuned(tuner) counterpoise.

Best,

Jack Painter
Virginia Beach, VA

In article , mike sebring wrote:
I live in S.E. Alaska on an island that is about 99% solid rock and i am
wondering what would be a good way to get an effective ground for my rig and
my antennas.
I have tried to drive a 4' ground rod in the ground and it will only go down
about a foot and a half till it hits solid rock.
I have considered just burying several strands of heavy bare copper wire and
using that for my ground.

The other answers confused an RF ground with an ELECTRICAL ground. For
better antenna usage, above ground, on the ground or in the ground
radial wires are the best thing. I have read several articles describing
the optium length for a radial, some go as short as 1/4 wave * velocity
factor, one went as long .28 wavelength. YMMV. Actual diameter of the
wire is not very important.

However you will still need an ELECTRICAL ground for lightening saftey
and static discharge. That should be as wide and as deep as possible. If
you can only go down 1.5 feet, then a 6 foot length of 1" copper pipe
layed horizontaly as far down as you can go would be a good idea. Ask a
local electrician.

You don't need to worry about wetting it or adding conductive agents to the
soil unless you have lightening storms when the ground is dry. Although I
live in the desert, I don't. When there is a lightening risk, the ground is
damp.

Geoff.

--
Geoffrey S. Mendelson, C.T.O. GW&T Ltd., Jerusalem Israel

IL Voice: 972-544-608-069 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838

"mike sebring" wrote in message ...
I live in S.E. Alaska on an island that is about 99% solid rock and i am
wondering what would be a good way to get an effective ground for my rig and
my antennas.
I have tried to drive a 4' ground rod in the ground and it will only go down
about a foot and a half till it hits solid rock.
I have considered just burying several strands of heavy bare copper wire and
using that for my ground.
Any sugjestions????
Thanks for any help any of you can give me.

Center-fed dipole-based antennas don't need station or installation
site RF grounds. Horizontally or vertically oriented. All end (base)
fed verticals need RF gounds so don't use 'em in your situation.
Safety gounding which is not RF grounding involves, in the limit,
tossing the feedlines out the window and ducking when boomers pass
thru the neighboorhood.

EX WB8RSH soon to be KL7???

Mike

w3rv

On Sat, 19 Jun 2004 20:27:42 +0000 (UTC), Geoffrey S. Mendelson wrote:
You don't need to worry about wetting it or adding conductive agents to the
soil unless you have lightening storms when the ground is dry. Although I
live in the desert, I don't. When there is a lightening risk, the ground is
damp.

Not in Idaho. That last several thunderstorms by me have all been dry.

sdb

--
| Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |
| Watch out for my e-mail address. Thank UCE. change ^ to @ |
It may be better to live under robber barons than under omnipotent moral
busybodies. The robber baron's cruelty may sometimes sleep, his
cupidity may at some point be satiated; but those who torment us for our
own good will torment us without end, for they do so with the approval
of their consciences. -- C. S. Lewis

"Sylvan Butler" wrote in message

Geoffrey S. Mendelson wrote:
You don't need to worry about wetting it or adding conductive agents to
the
soil unless you have lightening storms when the ground is dry. Although
I
live in the desert, I don't. When there is a lightening risk, the ground
is
damp.

Not in Idaho. That last several thunderstorms by me have all been dry.

sdb

In all but the sandiest soils, it could takes hours and hours of steady
rainfall to soak the ground more than a few inches. While good bonding is
arguably much more important than chasing a few ohms of earth ground
resistance, a dry hole is not much use as a ground point. I chose three of
my four (main) station ground points where it is always wet in the
thunderstorm season: the electric service ground and a bonding rod near it
are next to the HVAC condensate drain. A third one is next to a fish pond in
a naturally low and wet area. And the fourth main ground point has to be
watered and salted. To our poster in Alaska, I would suggest asking the
Electric company how they obtain good grounding in your particular area. And
then make sure you bond whatever system you sink in the ground to theirs as
well.

Best regards,

Jack Painter
Virginia Beach, VA

Brian Kelly wrote:


Center-fed dipole-based antennas don't need station or installation
site RF grounds. Horizontally or vertically oriented. All end (base)
fed verticals need RF gounds so don't use 'em in your situation.

I've never needed an rf ground for a base fed half wave. A decoupling
section with radials is an option to reduce feedline radiation..Not
required to work though. MK

--
http://web.wt.net/~nm5k

Mark Keith wrote in message ...
Brian Kelly wrote:


Center-fed dipole-based antennas don't need station or installation
site RF grounds. Horizontally or vertically oriented. All end (base)
fed verticals need RF gounds so don't use 'em in your situation.

I've never needed an rf ground for a base fed half wave. A decoupling
section with radials is an option to reduce feedline radiation..Not
required to work though. MK

You lost me Mark. You have a vertical half-wave wire fed at it's base.
You have an unbalanced L/C network which matches the very high
feedpoint impedance to, say, a random length of 50 ohm coax. What do
you do with the coax braid and the ground side of the tuner?

Brian w3rv

Brian Kelly wrote:

Mark Keith wrote in message ...
Brian Kelly wrote:


Center-fed dipole-based antennas don't need station or installation
site RF grounds. Horizontally or vertically oriented. All end (base)
fed verticals need RF gounds so don't use 'em in your situation.

I've never needed an rf ground for a base fed half wave. A decoupling
section with radials is an option to reduce feedline radiation..Not
required to work though. MK

You lost me Mark. You have a vertical half-wave wire fed at it's base.
You have an unbalanced L/C network which matches the very high
feedpoint impedance to, say, a random length of 50 ohm coax. What do
you do with the coax braid and the ground side of the tuner?

Brian w3rv

Using the usual "gamma loop" feed I generally prefer for those, the coax
shield is connected to the "ground" side of the single turn coil. "appx
9-11 inches dia. for a 10m version" I usually make these from 3/8
tubing... That point is at ground potential as far as the mast, base
support, etc..The other side of that coil is connected to the base of
the radiator. The center conductor taps the single turn coil at the
point for best match. A capacitor from ground to coil "hot" side is
optional. In general you use about 50 pf for a 10m version. Double for
20m, double again for 40m, etc... I use a piece of coax for those. "open
end, don't short" For 10m, it's only about a foot or so long...Look at a
cushcraft 10m ringo. "model AR-10". They have PDF manuals on the web
with pix..That is the same basic design I use. They also make 2m
versions...BTW, I make these from tubing, and are self supporting.
Rarely use wire...These antennas work quite well. Good 10m antenna...The
higher, the better..Add decoupling, even better, but not required to
work..MK
--
http://web.wt.net/~nm5k