Topband: 160m vertical saltwater grounding

[jh-mty at sbcglobal.net]

 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 at 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



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