Earth Antenna

[Nan and Sandy Sanders]

Frank, are you on http://tech.groups.yahoo.com/group/sub9khz/ ? They 
have some earth antenna topics.
      Sandy
     WB5MMB




At 11:05 AM 7/19/2013, Frank Eliot wrote:
>Gentlemen -
>
>         I had a fun time talking about one of my passions last 
> evening. Bill Liles sent me a note pointing out that in 1902, a Mr. 
> Nathan Stubblefield broadcast music from two stakes on the shore to 
> a boat in the Potomac. The receiver was two metal plates on the 
> hull of the boat at a 1/3 mile range .
>
>         I neglected to say this explicitly last night. I think that 
> dirt antennas (that is, where currents forced into the dirt 
> constitute the antenna, rather than buried wires), work because the 
> dirt has an intermediate resistance. Its resistivity is low enough 
> that you can force current to take a looping path through it, but 
> high enough so that the one turn loop antenna EM wave is not too 
> badly attenuated before it exits the ground. In the case of sea 
> water, or even the slightly-salty Potomac, I suspect that 
> propagation is purely via currents induced in the water, and not by 
> either magnetic induction or radiation. I suspect that with a much 
> higher powered transmitter than was available in 1902, and using 
> narrow-band detection techniques, that range could be substantially increased.
>
>Frank E
>
>
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