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Re: [TowerTalk] [Bulk] Re: Vertical Antennas near salt-water

To: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Re: Vertical Antennas near salt-water
From: Patrick Greenlee <patrick_g@windstream.net>
Date: Thu, 4 Feb 2016 13:07:22 -0600
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Professional HF SSB installations on wooden and Fiberglass boats typically use a "ground plate block" mounted external to the hull in contact with the sea water. These are often copper with fins like a heat sink to increase the area of contact with the water. Some ground plates are maybe 6-8, inches tall a foot long and a couple inches thick measured to the top of the fins. This may not be the best that can be done but is often what is done. I'm not sure how much degradation of the grounding occurs when marine growth fouls the surface of the ground plate but cleaning as necessary to keep the growth off is recommended. I used my monel shaft and bronze propeller for electrical contact to the sea and the engine and transmission bonded in as additional counterpoise. Worked well but risked lightning going through the auxiliary engine and welding the shaft to the bearings or similar.

Patrick        NJ5G

On 2/3/2016 9:32 PM, Gary Schafer wrote:
Unfortunately the article does not mention a vertical mounted OVER salt
water. Laying a small number of radials on the sand or coral rock near the
water is not going to give a very good connection to the salt water. That
was apparently evidenced by the detuning of the radials.

Since the skin effect of salt water is only a few inches deep, laying few
radials in the water would not provide much benefit. You would only have the
connection to the water within a few inches of where the wires enter the
water.

Several years ago when I lived in Florida I had a 40 meter vertical mounted
to one of the dock posts over the water. The base of the vertical was about
2 to 3 feet above the water depending on the tide. I had a large bare
aluminum plate 2 feet wide by about 6 feet long placed vertically into the
water right below the antenna. This was the ground connection to the water.
It only takes a couple of square feet of water contact to realize a good
ground connection.
The impedance at antenna resonance was right close to 36 ohms with no
matching device. I used a small coil and cap to match to 50 ohms. It worked
very well.
Of course as the tide level changed so did the resonant frequency as the
length of the ground plate to water was changing.

73
Gary  K4FMX

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Mike Ryan
Sent: Wednesday, February 03, 2016 4:56 PM
To: Bill
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Re: Vertical Antennas near salt-water

There has been a ton of talk on this subject. I myself live on a salt
water
canal in Florida and have tried various vertical antennas over the salt
water, aside it, next to it, etc.  There is so much MISINFORMATION and
downright speculation based on wrong assumptions, guesswork, and the
like.
Someone did a great article on the subject who was in fact a contester.
(Should that be spelled contestor, or contestee? ..you decide)  At any
rate,
if you read article which can be opened from the link I have attached,
play
close attention to the paragraph that reads
" ... often incorrect assumptions about verticals: ".  This is
enlightening
but the information is based on success or failure in the field and not
supposition which in my OPINION counts for something!  -Mike

Subject: verticals

http://www.k2kw.com/verticals/learning.html




-----Original Message-----
From: Bill
Sent: Wednesday, February 03, 2016 2:55 PM
To: Towertalk Mailing List
Cc: Chuck Dietz
Subject: Re: [TowerTalk] [Bulk] Re: Vertical Antennas near salt-water

My HF2V and Butternut 6 BTV are both attached to metal posts at my sea
wall. Both posts go into the salt water. They work at 1:1 SWR with no
radials. I do have some in the water but always wonder why? Hi...

They both perform very well and load on all bands.
Bill W2CQ



On 2/3/2016 2:30 PM, Chuck Dietz wrote:
I had a vertical for 160 on a small peninsula in salt water. I ran the
radials into salt water in 4 directions and pushed aluminum tubing
pieces
into the bottom in the salt water with the end of the radials clamped
to
them. Awesome antenna on transmit. Fair on receive. Just need enough
radial
length to get to the salt water.

Chuck W5PR

On Wednesday, February 3, 2016, Gary K9GS <garyk9gs@wi.rr.com> wrote:

I had an interesting discussion with a friend over the weekend and
wanted
to get some input from the TowerTalk community.

Imagine a 1/4 wavelength wire hanging down from a tree with the
bottom
end
attached to a post set into the salt water.  The antenna wire would
be 3
or
4 feet above the water.  What should be done with the
radial/counterpoise
wires?  Should those wires go into the water?

Or imagine a similar hanging wire that has the bottom end attached to
the
top of a seawall.  Again, the bottom of the antenna would be 3-4 feet
above
the water.  Should the radials run on the ground parallel to the
seawall
or
run into the water?

A third situation would be a vertical antenna mounted at the end of a
pier.  Run the radials back toward shore along the pier or run all of
the
radials into the water?

Finally, if the radials are in the water does it make any difference
if
the wire is insulated or not?


--
73,

Gary K9GS

Greater Milwaukee DX Association: http://www.gmdxa.org
Society of Midwest Contesters: http://www.w9smc.com
CW Ops #1032   http://www.cwops.org

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