Topband: 160m vertical saltwater grounding

[Robert Fanfant]

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