New antenna

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New antenna

Jan Erik Holm
This will go nicely with my K3
http://www.youtube.com/watch?v=9tIZUhu21sQ

73 Jim SM2EKM
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Re: New antenna (OT ?)

Phil Kane-2
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

  This has been debunked by antenna design experts (one of whom
  is a staff member of my company) as "voodoo electronics"
  because of the extreme losses in the conductivity of seawater
  versus that of the metals usually used in antennas.

  Better try next time....

--  73 de K2ASP - Phil Kane
    Elecraft K2/100   s/n 5402

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Re: New antenna (Definitely OT)

Kok Chen
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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Re: New antenna (Definitely OT)

AC7AC
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Re: New antenna (Definitely OT)

Carl W Clawson
In reply to this post by Kok Chen
There's another warning sign in the text accompanying the video. My
pseudoscience alarm went off when I read the following:

"SPAWAR Systems Center Pacific has developed a technology that uses the
magnetic induction properties of sodium chloride (salt) in sea water to
create UHF/VHF/HF antenna."

This is meaningless jargon...magnetic properties of salt or salt water have
nothing to do with it.

The aforementioned alarm is always triggered by "magnetic" being used in
conjunction with "antenna."

73 and thanks for listening,
Carl WS7L
K3 #486

> -----Original Message-----
>
> > 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!
> ...
> ...
> This could make a good water heater.  All that power has to go
> *somewhere* :-).

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Re: New antenna (Definitely OT)

David Gilbert
In reply to this post by Kok Chen


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
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
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