Hi Andy, yes I was just given a book (rescued from the skip when the BTRL
library closed !!) by an ex-collegue from BTRL titled "ELF Communication
Antennas" by Burrows (pub IEE) It does make very interesting reading, and
explains a lot about the "myth" of "underground dipoles". These antenna are
similar to those used by John G3PAI and CREG people and the do radiate LF
signals "through the air" Though not as efficiently as normal amateur sized
verticals.
How is the 9kHz NoV comming along ??
Alan
----- Original Message -----
From: "Andy" <[email protected]>
To: <[email protected]>
Sent: 30 March 2005 08:05
Subject: LF: Re: Re: low long wire as TX-antenna???
I think you can go a bit further with that Alan. If you have a really
long, low, wire then the current is returned via the ground, penetrating
down to skin depths. The result is a big loop, with the dimensions of
(effective) skin depth * length of wire. So resulting in vertical
polarisation.
This was (still is ??) the type of antenna used by the US at ULF (67 Hz,
81
Hz ???) for their submarine communications. Wires that look like
overhead telephone cables disappearing for hundreds of km into the
distance!
If you want a bit of fun reading conspiracy theorists ranting, do a
Google
search for "ULF" to find out about the government's mind numbing radiation
experiments !
Andy G4JNT
>hear some of the pundits sharpening their pencils....it is actually not
that
>simple, as the ground level is not the level of the "Earth-plate" you
must
>take into effect the skin depth of the ground at this frequency. This is
>dependent upon the frequency and nature of the soil. Thus at ELF (<
3kHz),
>the type of antenna you think of will work quite well (compared with
>anything else) the skin depth is proportional to the frequency but the
>radiation resistance is proportional to the (frequency)^2. I think you
said
>you ground was poor, sandy. That would work to some extent if there were
no
>surrounding lossy "environment"....like trees shrubs and houses. I
suspect
>this is why the VK antenna across the valley that Bob describes works so
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