I think the answer to this Roger is "you will have to try it" The ground
antenna is dependent on the actual parameters of the ground below you. It can
be considered as a vertical loop .....the connection being the "top" or the
loop. Over conductive soil it won't work too well, but over poor ground it can
be quite effective. The problem with these variables (what is the real skin
depth ?) is calculating the ERP, and so knowing what power you will need. Then
what about underground cables and pipes?? Verticals are a doddle to calculate
by comparion.
As with previousl experiments, the trials can be easier than the calculations.
Alan
--- On Tue, 16/3/10, Roger Lapthorn <[email protected]> wrote:
> From: Roger Lapthorn <[email protected]>
> Subject: LF: 8.97kHz antennas
> To: [email protected]
> Date: Tuesday, 16 March, 2010, 13:59
> Getting a Marconi vertical up in the sky is
> no mean task when 100m long and carrying a decent antenna
> current so I was wondering whether there is any merit in
> using grounded electrode pairs (as used for
> through-the-ground "earth mode" conduction tests)
> possibly fed with elevated feed wires as an alternative?
>
>
> Not being much of a theory man I've little idea how
> this would perform and what amount of the 8.97kHz energy
> injected into the loop thus formed would actually be
> radiated. Clearly stringing out a 200m long grounded
> electrode pair "antenna" in a big field would be
> considerably easier than raising a kite mounted vertical.
> This arrangement on a much larger scalle was used at 76Hz
> for Project Sanguine (to radiate a signal to submarines,
> deeply submerged) and papers I've read on "earth
> mode" caution that for military applications the
> through-ground path may not be secure because of the amount
> of energy radiated. I also recall that G0AKN used this
> arrangement with some success on 73kHz.
>
>
> Anyone know the answer?
>
> 73s
> Roger G3XBM
> --
>
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
>
> http://www.youtube.com/user/G3XBM
> G3XBM GQRP 1678 ISWL G11088
>
>
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