Finally, many DXpeditioners listening in will have had extensive experience
with temporary/vacationer salt water vertical systems, and can chime in with
additional observations and advice. Good luck, and have a great vacation...JH
W6UQZ
On Wednesday, January 8, 2020, 03:56:54 PM PST, jh-mty@sbcglobal.net
<jh-mty@sbcglobal.net> wrote:
Just FYI, I ditched all that wire coupling nonsense when it became clear that
the ocean itself simply being underneath was the major enhancement, with no
additional coupling needed for a complete (radial/counterpoise) vertical
antenna located above a fair amount of salt seawater. Absent that scenario,
you can use the ocean as the counterpoise system with the coupling wires, but I
believe that converts your vertical monopole into the equivalent of a vertical
dipole....either of which will absolutely amaze you IF you are over salt water,
around 15-20' depth at the pier in my case.
----- Forwarded Message ----- From: jh-mty@sbcglobal.net
<jh-mty@sbcglobal.net>To: topband@contesting.com <topband@contesting.com>;
Robert Fanfant <rfanfant@hotmail.com>Sent: Wednesday, January 8, 2020, 03:48:12
PM PSTSubject: Re: Topband: 160m vertical saltwater grounding
Just bare copper wire with washers or lead fishing weights tied on the ends
is just fine if you wish to enhance coupling between the vertical and the salt
water, or 4 raised counterpoise wires in the air will also work extremely well.
The main issue is to position the vertical over the near-perfect salt water
ground vs the terrestrial.
I used to operate /M 160 from the Monterey (CA) commercial pier, and the salt
water was amazing for brewster angle and enhanced RX, even with the vehicle 15'
up over the water. Your setup as envisioned with "Floating plate" coupling
will be a maintenance nightmare and will last exactly ONE storm. Use the KISS
principle when it comes to salt-water vertical installations!
I laughed when tourists used to pull on the washer-weighted wires hanging off
the base of my 160 Pro-Am stick thinking I was crab fishing from the pier.
Come to think of it, I should've attached a turkey leg to that wire and made it
dual purpose!!
Best, John H W6UQZ
On Wednesday, January 8, 2020, 02:30:16 PM PST, Robert Fanfant
<rfanfant@hotmail.com> wrote:
Am looking to activate a location with very limited space surrounded by ocean.
Think of a small rock surrounded by saltwater/ocean. The vertical will be a
tall 60’+ fiberglass pole and made to resonate on 160m. I would like a way to
reduce the required space of the 160m antenna radial field due to the limited
physical space available. The vertical will be located at the waters edge, or
even possibly over the oceans surface. At the feed point, will be a choke
designed for 160m. We should also assume maximum power of 1.5KW being fed into
the vertical and the activation will be for a 2 week duration of time.
One idea that came up is to use a floating piece of conductive material as the
verticals counterpoise. Specifically, a thin conductive plate designed to
float on the oceans surface. From the antenna’s feed point, will be a short
length of ground wire say about 6’ long, to this conductive plate.
Question(s):
1. Is it possible to just use the ocean as the ground plane / counterpoise ?
That is, can this idea work?
2. If so,
* How do I determine the required square footage/size of the plate?
* What material should be used as the conductive plate? (Nickel, copper,
aluminum, etc..? )The thought here is to make this plate as light as possible,
yet effective. It will need to last the duration of the activation (~2 weeks)
in/on saltwater, it needs to handle 1.5KW at the feed point, and likely exposed
to air and saltwater as it floats on the ocean surface.
-rob N7QT
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|