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Message-ID: <910844.27140.qm@web86505.mail.ird.yahoo.com>
Date: Tue, 16 Mar 2010 19:36:15 +0000 (GMT)
From: ALAN MELIA <alan.melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <9afca2641003160659r4a659ae5re0a7a46ca1ba9f43@mail.gmail.com>
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Subject: Re: LF: 8.97kHz antennas
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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 pow=
er 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 calculati=
ons.

Alan

--- On Tue, 16/3/10, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:

> From: Roger Lapthorn <rogerlapthorn@gmail.com>
> Subject: LF: 8.97kHz antennas
> To: rsgb_lf_group@blacksheep.org
> 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?=20
>=20
>=20
> 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.
>=20
>=20
> Anyone know the answer?
>=20
> 73s
> Roger G3XBM
> --=20
>=20
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
>=20
> http://www.youtube.com/user/G3XBM
> G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
>=20
>=20