Return-Path: Received: from mtain-dg03.r1000.mx.aol.com (mtain-dg03.r1000.mx.aol.com [172.29.65.11]) by air-mb05.mail.aol.com (v129.4) with ESMTP id MAILINMB051-a3834c3f756b8b; Thu, 15 Jul 2010 16:54:03 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dg03.r1000.mx.aol.com (Internet Inbound) with ESMTP id C92D0380002EE; Thu, 15 Jul 2010 16:54:00 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OZVPz-0000QR-BO for rs_out_1@blacksheep.org; Thu, 15 Jul 2010 21:52:31 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OZVPy-0000QI-OS for rsgb_lf_group@blacksheep.org; Thu, 15 Jul 2010 21:52:30 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OZVPw-0006TN-VZ for rsgb_lf_group@blacksheep.org; Thu, 15 Jul 2010 21:52:30 +0100 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id o6FKqR47026333 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 15 Jul 2010 22:52:27 +0200 Received: from extmail.urz.uni-heidelberg.de (extmail.urz.uni-heidelberg.de [129.206.100.140]) by ix.urz.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id o6FKqROC018552 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 15 Jul 2010 22:52:27 +0200 Received: from [147.142.13.222] (vpn513-222.rzuser.uni-heidelberg.de [147.142.13.222]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id o6FKq9U6023586 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 15 Jul 2010 22:52:11 +0200 Message-ID: <4C3F7519.6020400@iup.uni-heidelberg.de> Date: Thu, 15 Jul 2010 22:52:41 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.10) Gecko/20100512 Thunderbird/3.0.5 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4C363DCD.303@iup.uni-heidelberg.de> <4C3650A1.6040104@iup.uni-heidelberg.de> <4C3DA75D.80407@iup.uni-heidelberg.de> <263121BD51374246B3F184A43B2E9619@JimPC> <4C3E27D4.3060407@iup.uni-heidelberg.de> <3F71CB69-5F2E-4BEE-BB5E-651DA77CC39E@numeo.fr> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: RE: DLF passive received with earth antenna Content-Type: multipart/alternative; boundary="------------080204050307060306030107" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_FONTCOLOR_UNSAFE, HTML_MESSAGE,HTML_TITLE_EMPTY 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-sid: 3039ac1d410b4c3f75687e10 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --------------080204050307060306030107 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hello Roger, VLF, Maybe it will give us some ideas of the propagation of such an earth antenna if i try to receive even lower frequencies on my grabber QTH. Then we can see if the effective area increases when the frequency goes down. With the high power PA (H-bridge) i could try 8...7...6...5.......0 kHz and will see where the cut off frequency will be. But since i mainly want to concentrate on the dreamers band, the 50km distance to Michael Oexner is a more important goal for me :-) Roger, any news from your side? Tnx for bringing up the discussion of the earth antennas! :-) 73, Stefan/DK7FC Am 15.07.2010 20:07, schrieb Roger Lapthorn: > This sounds an interesting talk. Where is this conference being held > please? > > Perhaps with Heyphones and Nicola systems working in the 40-90kHz > region these antennas do behave differently. At 500kHz I'm convinced > the earth electrode structure behaves as a loop based on the reports > I've received and directionality. I suspect the same is true at 136kHz . > > At ELF/VLF I think the earth electrode pair must act in several ways > simultaneously. > > (a) As an induction loop. This certainly ties up with behaviour and > loop orientation locally in my experiments away from buried cables. > > (b) As a means of producing a potential difference in the ground for > earth mode (conduction) communication. Again, this is how I understand > my "utilities assisted DX" is being achieved on 838Hz with the signal > being largely conducted along buried pipework and cables and the last > few metres being inductively coupled into my loop receiver. I can't > see how else just 4W can get so far. > > (b) As an inefficient and lossy dipole radiating a tiny signal. > > It would be most interesting to read about the ELF antennas used for > Project Sanguine and the theory behind these. These (miles long) > antennas were grounded at each end and the grounding was important for > the system to radiate an ELF signal detectable in the deep oceans at > 76Hz. > > Has Dr Gibson written anything already to give us a clue what he > thinks is going on? > > 73s > Roger G3XBM > > > On 15 July 2010 17:52, John Rabson > wrote: > > Members of the Cave Radio & Electronics Group have been using and > investigating earth loop antennas for some time. The theoretical > basis of such an antenna has not been clear to us, but Dr David > Gibson of CREG is proposing to give the following lecture at the > Hidden Earth conference in the UK this autumn. > > How earth-current antennas really work > -------------------------------------- > With cave radio equipment such as the HeyPhone and Nicola system there > has been a trend away from the use of induction loop antennas towards > earth-current antennas, i.e. long wires grounded at both ends. > However, > the popular explanation for how these antennas work is fallacious. > They > do not operate by allowing the current to flow in a 'big loop' in the > ground and in fact, they do not depend, fundamentally, on current flow > in the ground at all. > > The fact that the popular explanation is wrong is important > because, if > we do not understand how the antenna works, it is difficult to > know the > best way to use it, or how to design a better one. Back in 2003, I > wrote > an article for the CREG journal entitled 'What We Don't Know About > Earth-Current Propagation'. It has taken me some time to get to grips > with the problem but this talk will now go some way to filling in the > gaps in this knowledge and will describe a method of experimentally > rating earth-current antennas for effectiveness. > > -- > David Gibson > > > > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > G3XBM GQRP 1678 ISWL G11088 --------------080204050307060306030107 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hello Roger, VLF,

Maybe it will give us some ideas of the propagation of such an earth antenna if i try to receive even lower frequencies on my grabber QTH. Then we can see if the effective area increases when the frequency goes down. With the high power PA (H-bridge) i could try 8...7...6...5.......0 kHz and will see where the cut off frequency will be.
But since i mainly want to concentrate on the dreamers band, the 50km distance to Michael Oexner is a more important goal for me :-)

Roger, any news from your side? Tnx for bringing up the discussion of the earth antennas! :-)

73, Stefan/DK7FC

Am 15.07.2010 20:07, schrieb Roger Lapthorn:
This sounds an interesting talk. Where is this conference being held please?

Perhaps with Heyphones and Nicola systems working in the 40-90kHz region these antennas do behave differently.  At 500kHz I'm convinced the earth electrode structure behaves as a loop based on the reports I've received and directionality. I suspect the same is true at 136kHz .

At ELF/VLF I think the earth electrode pair must act in several ways simultaneously.

(a) As an induction loop. This certainly ties up with behaviour and loop orientation locally in my experiments away from buried cables.

(b) As a means of producing a potential difference in the ground for earth mode (conduction) communication. Again, this is how I understand my "utilities assisted DX" is being achieved on 838Hz with the signal being largely conducted along buried pipework and cables and the last few metres being inductively coupled into my loop receiver. I can't see how else just 4W can get so far.

(b) As an inefficient and lossy dipole radiating a tiny signal.

It would be most interesting to read about the ELF antennas used for Project Sanguine and the theory behind these. These (miles long) antennas were grounded at each end and the grounding was important for the system to radiate an ELF signal detectable in the deep oceans at 76Hz.

Has Dr Gibson written anything already to give us a clue what he thinks is going on?

73s
Roger G3XBM


On 15 July 2010 17:52, John Rabson <john.rabson@numeo.fr> wrote:
Members of the Cave Radio & Electronics Group have been using and investigating earth loop antennas for some time. The theoretical basis of such an antenna has not been clear to us, but Dr David Gibson of CREG is proposing to give the following lecture at the Hidden Earth conference in the UK this autumn.

How earth-current antennas really work
--------------------------------------
With cave radio equipment such as the HeyPhone and Nicola system there
has been a trend away from the use of induction loop antennas towards
earth-current antennas, i.e. long wires grounded at both ends. However,
the popular explanation for how these antennas work is fallacious. They
do not operate by allowing the current to flow in a 'big loop' in the
ground and in fact, they do not depend, fundamentally, on current flow
in the ground at all.

The fact that the popular explanation is wrong is important because, if
we do not understand how the antenna works, it is difficult to know the
best way to use it, or how to design a better one. Back in 2003, I wrote
an article for the CREG journal entitled 'What We Don't Know About
Earth-Current Propagation'. It has taken me some time to get to grips
with the problem but this talk will now go some way to filling in the
gaps in this knowledge and will describe a method of experimentally
rating earth-current antennas for effectiveness.

--
David Gibson




--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM    GQRP 1678      ISWL G11088
--------------080204050307060306030107--