[Lowfer] Experimental antenna?

[Stewart Nelson]

Hi Pat,

This is sometimes called an "earth loop antenna".  In addition to
the VLF military and amateur applications mentioned, it has been
used at LF for cave rescue systems.
See http://www.sat.dundee.ac.uk/~arb/heyphone/ .
That system runs at 87 kHz.

In the US, the FCC part 15 rules would limit the spacing between
the pipes to about 50 feet.  There is also less earth penetration
in the lowfer band, so you would end up with a radiation resistance
no more than that of an Ashlock loop, probably much less.  However,
the loss resistance would be at least an order of magnitude higher.
IMO, a few hundred microwatts ERP is all you could expect.

I don't know what rules apply in Canada, but if a much larger spacing
would be permitted, you might get decent efficiency.  If a loop or
a vertical is limited to a very low height, or if the antenna must not
be visible, it is possible that the earth loop would be the best choice.

73,

Stewart


----- Original Message ----- 
From: "Patrick MacKinnon" <pat2002@foxhollow.ca>
To: <lowfer@mailman.qth.net>
Sent: Monday, February 24, 2003 7:21 PM
Subject: [Lowfer] Experimental antenna?


> I've been a ham for 15 years, but very new to this list, and will probably
> brew up a lowfer transmitting rig/antenna this summer. Forgive this newbie
> question, but:
> 
> Has anyone tried water drilling two parallel copper pipes into the earth and
> using this as a transmitting antenna? It just seems to me that would be a
> very effective way of inducing LF currents into the ground. (A fellow ham
> told me he recently attended a club presentation on VLF and he stated the
> earth itself carries the signal. Is this true or did he mis-hear something?)
> [or am I so far off base here I'm in for the flaming of a lifetime?
> remember: please be kind, I'm new to this! :)  ]
> 
> Thanks!
> Pat, VE3PMK
> London, ON, Canada
> 
> 
> 
> ###########
> PLEASE NOTE:
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> -- Pat MacKinnon
>  
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