Return-Path: Received: from mtain-de02.r1000.mx.aol.com (mtain-de02.r1000.mx.aol.com [172.29.64.202]) by air-me02.mail.aol.com (v129.4) with ESMTP id MAILINME024-8ba74d4b0ba625; Thu, 03 Feb 2011 15:10:14 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-de02.r1000.mx.aol.com (Internet Inbound) with ESMTP id B5FB938000155; Thu, 3 Feb 2011 15:10:12 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Pl5UK-0000xo-5T for rs_out_1@blacksheep.org; Thu, 03 Feb 2011 20:09:08 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Pl5UJ-0000xf-4z for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 20:09:07 +0000 Received: from filter02.i-online.fr ([195.200.78.9]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Pl5UI-0000dD-2X for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 20:09:07 +0000 Received: from smtp.qtxt.dns-iol.com ([195.200.78.13]) by filter02.i-online.fr (IceWarp 10.0.7 (2010-02-10)) with ESMTP (SSL) id MWL26947 for ; Thu, 03 Feb 2011 21:08:47 +0100 Received: (qmail 1245 invoked by uid 507); 3 Feb 2011 21:08:45 +0100 Received: from unknown (HELO ?192.168.1.103?) (john.rabson@numeo.fr@217.67.155.178) by smtp.qtxt.dns-iol.com with SMTP; 3 Feb 2011 21:08:45 +0100 Mime-Version: 1.0 (Apple Message framework v1082) From: John Rabson In-Reply-To: Date: Thu, 3 Feb 2011 21:08:56 +0100 Message-Id: References: To: rsgb_lf_group@blacksheep.org X-Mailer: Apple Mail (2.1082) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Content-Type: text/plain; charset=us-ascii Subject: Re: LF: Earth-mode or not earth-mode Content-Transfer-Encoding: quoted-printable 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=none 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: 3039ac1d40ca4d4b0ba40f96 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Some years ago, we tried using a small loop to couple a Heyphone (4 W outp= ut on 87 kHz) into a running rail in a disused railway tunnel in the Engli= sh Midlands (we had permission from the owners of the line). A similar se= tup was used for receive and we achieved a range of 1.6 km along the line. 73 John F5VLF On 3 Feb 2011, at 20:36CET, Jacek Lipkowski wrote: > trying to couple to large structures is an interesting experiment, both= for receiving and transmitting (only by induction of course :). think abo= ut power lines, phone lines (but unfortunately nowadays most are very shor= t, and the rest is done via fiber), natural gas pipelines, railways etc.= this is an example rx experiment: http://www.youtube.com/watch?v=3DsWsdaS= mWg7E , these structures are usually very well grounded at regular interva= ls, but still some vlf will slip through the ground system, so they can be= also used for tx too. a few miliamps at 9kHz into a large structure is de= tectable from a few hundred meters. >=20 > actually the "utilities-assisted earth mode" works not only on transmit.= a loop antenna near a long conductor will pick up a stronger signal (and= also more qrm, so this doesn't always raise S/N). >=20 > this might not be ham radio (or not radio at all), but is very interesti= ng nevertheless >=20 > VY 73 >=20 > Jacek / SQ5BPF >=20 >=20