Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: from mtain-me07.r1000.mx.aol.com (mtain-me07.r1000.mx.aol.com [172.29.96.143]) by air-md01.mail.aol.com (v127_r1.1) with ESMTP id MAILINMD013-8b764b9b5a9d206; Sat, 13 Mar 2010 04:27:57 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-me07.r1000.mx.aol.com (Internet Inbound) with ESMTP id 9DCBE38000085; Sat, 13 Mar 2010 04:27:55 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NqNc4-0002f0-2v for rs_out_1@blacksheep.org; Sat, 13 Mar 2010 09:26:28 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NqNc3-0002er-K2 for rsgb_lf_group@blacksheep.org; Sat, 13 Mar 2010 09:26:27 +0000 Received: from 113-mo2-8.acn.waw.pl ([62.121.95.113] helo=paranoid.lipkowski.org) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from <sq5bpf@lipkowski.org>) id 1NqNc1-0000qj-8R for rsgb_lf_group@blacksheep.org; Sat, 13 Mar 2010 09:26:27 +0000 Received: from paranoid.lipkowski.org (localhost [127.0.0.1]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id o2D9EUmD031745 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for <rsgb_lf_group@blacksheep.org>; Sat, 13 Mar 2010 10:14:30 +0100 Received: from localhost (sq5bpf@localhost) by paranoid.lipkowski.org (8.13.7/8.13.6/Submit) with ESMTP id o2D9EUYq031742 for <rsgb_lf_group@blacksheep.org>; Sat, 13 Mar 2010 10:14:30 +0100 X-Authentication-Warning: paranoid.lipkowski.org: sq5bpf owned process doing -bs Date: Sat, 13 Mar 2010 10:14:30 +0100 (CET) From: Jacek Lipkowski <sq5bpf@lipkowski.org> To: rsgb_lf_group@blacksheep.org In-Reply-To: <9709F1D41FF74661B0771F657988884F@JimPC> Message-ID: <Pine.LNX.4.64.1003130958310.19701@paranoid.lipkowski.org> References: <9afca2641003111254v47a0363eicdee899d7c2b3431@mail.gmail.com> <9709F1D41FF74661B0771F657988884F@JimPC> MIME-Version: 1.0 X-Spam-Score-sq5bpf: -2.601 () BAYES_00,SPF_HELO_PASS,SPF_PASS X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re: Induction DX? Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed 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: 3039ac1d608f4b9b5a9b4a2f X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) On Thu, 11 Mar 2010, James Moritz wrote: > It is interesting to try to work out what might be possible by induction... [...] have a look at http://www.home.pon.net/785/equipment/transmitting/VLF_transmit_2.htm this experiment used two triangular loops of 15m high and 90m circumfrence in a natural area (without conductors etc). the author was able to copy a 0.5W cw signal at the distance of 3.3km! this is much more, than what is expected from free-space calculations mentioned in this thread. this is probably the effect of the ground (currents induced in the ground excite some much bigger ground loops that make up a "secondary" antenna of bigger size). another explamantion would be that the field induced at the transmitter site got into the 2m receiver that the author was using, but i hope that is not the case :) VY 73 Jacek / SQ5BPF