[Elecraft] New antenna (Definitely OT)

[David Gilbert]

Actually, a pretty casual Google search will turn up homebrew designs 
using a can of high-concentration salt water as an inexpensive (though 
not very stable) dummy load.

And that's pretty much what the salt water "antenna" would be.

73,
Dave   AB7E



On 10/17/2010 11:30 AM, Kok Chen wrote:
> On 10/17/2010 1:40 AM, Jan Erik Holm wrote:
>
>> This will go nicely with my K3
>> http://www.youtube.com/watch?v=9tIZUhu21sQ
> Seawater has electrical conductivity of seven *orders* of magnitude
> lower than copper!
>
> As a quick and dirty check, I created a simple 10m ground plane
> antenna in NEC-4.  Four counterpoises and a vertical radiating element
> that is bottom fed, all of equal lengths, with the counterpoises and
> the feedpoint 1m above seawater (natch!) ground.  All elements 0.5" in
> diameter.
>
> With perfectly conducting elements, the feedpoint impedance is just
> about 35 ohms, with a gain of 4.7 dBi.
>
> When I changed the conductivity of the vertical element to 5 mhos/
> meter, while keeping the counterpoises as perfectly conducting, the
> computed gain dropped to -8.2 dBi and the feedpoint impedance is
> capacitive at 320 -i*250 ohms.
>
> I.e., something like 13 dB loss compared to using copper elements.
>
> BTW, I could not achieve resonance by extending the length of the
> radiating element --  I guess you will need a KAT500 in addition to
> that KPA500 which you use to make up for the missing 13 dB.
>
> This could make a good water heater.  All that power has to go
> *somewhere* :-).
>
> 73
> Chen, W7AY
>
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