Return-Path: Received: from mtain-dd08.r1000.mx.aol.com (mtain-dd08.r1000.mx.aol.com [172.29.64.148]) by air-de07.mail.aol.com (v127_r1.1) with ESMTP id MAILINDE074-5ebd4b9fe4a04b; Tue, 16 Mar 2010 16:05:52 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dd08.r1000.mx.aol.com (Internet Inbound) with ESMTP id B6BB5380000B1; Tue, 16 Mar 2010 16:05:50 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Nrd0U-0007Bt-Ox for rs_out_1@blacksheep.org; Tue, 16 Mar 2010 20:04:50 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Nrd0U-0007Bk-37 for rsgb_lf_group@blacksheep.org; Tue, 16 Mar 2010 20:04:50 +0000 Received: from mail-bw0-f210.google.com ([209.85.218.210]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Nrd0P-0006Q5-Sj for rsgb_lf_group@blacksheep.org; Tue, 16 Mar 2010 20:04:50 +0000 Received: by bwz2 with SMTP id 2so348567bwz.30 for ; Tue, 16 Mar 2010 13:04:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=7dymK5iBOWCO0e9p/uXxBggCHx+UOj+x6fUHo/4DJfA=; b=GYckkLA8krU5CAKOR/DqU+bybOtmalRWFE67aFkeeppllEwaGbQqAvC9h/O3OWwPJI GvCaJAwPl1WPLIWf0tjxzmLua2N+rKFyOy589afKSSkEJq8/roUdRyxClEJ/VeUb/4Eg UwvLo7z+ONu0Vyv93DE3BmfuqtQwqzhLU4eZE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=Yd0TwmGr16XiRBJyNapp/OahDGsv21lZnj8aQpOJpKdu0Q4tcTCVNfo/aJ3YpNnh4I UVrtivLWN0GELjawgXrl4LdkjoMw3mFY7a9131MeaPJ52945wVm7ZN7OYLk8y+CINu6E nLJibUed4HQzOoHzL+bSTbeE9R6NpZ9H3/cQA= MIME-Version: 1.0 Received: by 10.204.25.209 with SMTP id a17mr23633bkc.104.1268769879644; Tue, 16 Mar 2010 13:04:39 -0700 (PDT) In-Reply-To: <910844.27140.qm@web86505.mail.ird.yahoo.com> References: <9afca2641003160659r4a659ae5re0a7a46ca1ba9f43@mail.gmail.com> <910844.27140.qm@web86505.mail.ird.yahoo.com> Date: Tue, 16 Mar 2010 20:04:39 +0000 Message-ID: <9afca2641003161304u339c11f4w91c351e5c42b106a@mail.gmail.com> From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: 8.97kHz antennas Content-Type: multipart/alternative; boundary=000325557e1efa5d4b0481f081d1 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d270.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40944b9fe49e39ad X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --000325557e1efa5d4b0481f081d1 Content-Type: text/plain; charset=ISO-8859-1 Thanks Alan. Yes I can understand that poor ground conductivity would result in a larger loop within the ground and that with high conductivity the loop would be very small. With regard to piping and cables, I'm thinking that any such tests would have to be done well away from buildings and property ideally in the middle of a large field out in the country or on a stretch of moorland perhaps well away from cables and pipes. In an urban area cables and pipes are everywhere and anything could be happening. 73s Roger G3XBM On 16 March 2010 19:36, ALAN MELIA wrote: > 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 wrote: > > > From: Roger Lapthorn > > 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? > > > > > > 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 > > > > > > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --000325557e1efa5d4b0481f081d1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Thanks Alan.

Yes I can understand that poor ground conductivity wo= uld result in a larger loop within the ground and that with high conductiv= ity the loop would be very small. With regard to piping and cables, I'= m thinking that any such tests would have to be done well away from buildi= ngs and property ideally in the middle of a large field out in the country= or on a stretch of moorland perhaps well away from cables and pipes. In= an urban area cables and pipes are everywhere and anything could be happe= ning.

73s
Roger G3XBM




On 16= March 2010 19:36, ALAN MELIA <alan.melia@btinternet.com> wrote:
=
I think the answer to this Roger is "you will have to try it" Th= e ground antenna is dependent on the actual parameters of the ground below= you. It can be considered as a vertical loop .....the connection being th= e "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 th= ese 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 calculati= ons.

Alan

--- On Tue, 16/3/10, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:

> From: Roger Lapthorn <r= ogerlapthorn@gmail.com>
> Subject: LF: 8.97kHz antennas
> To: rsgb_lf_group@bla= cksheep.org
> Date: Tuesday, 16 March, 2010, 13:59
> Getting a Marconi vertical up in th= e 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://g= 3xbm-qrp.blogspot.com/
> http://www.g3xbm= .co.uk
>
> http:= //www.youtube.com/user/G3XBM
> G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
>
>




--

http://g3xbm-qrp.blogspot.com/http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--000325557e1efa5d4b0481f081d1--