Return-Path: Received: from mtain-mi10.r1000.mx.aol.com (mtain-mi10.r1000.mail.aol.com [172.21.131.168]) by air-db05.mail.aol.com (v129.4) with ESMTP id MAILINDB054-86994d4c4ecdc1; Fri, 04 Feb 2011 14:09:01 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mi10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4C2EB3800010A; Fri, 4 Feb 2011 14:08:59 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PlR12-00061d-59 for rs_out_1@blacksheep.org; Fri, 04 Feb 2011 19:08:20 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PlR11-00061U-Ox for rsgb_lf_group@blacksheep.org; Fri, 04 Feb 2011 19:08:19 +0000 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PlR10-0001zu-L5 for rsgb_lf_group@blacksheep.org; Fri, 04 Feb 2011 19:08:19 +0000 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p14J8HBQ008612 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 4 Feb 2011 20:08:17 +0100 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 p14J8Hg7005004 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 4 Feb 2011 20:08:17 +0100 Received: from [129.206.196.153] (vpn153a.rzuser.uni-heidelberg.de [129.206.196.153]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id p14J8Ehc007431 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 4 Feb 2011 20:08:16 +0100 Message-ID: <4D4C4EB6.6060407@iup.uni-heidelberg.de> Date: Fri, 04 Feb 2011 20:08:38 +0100 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Earth-mode or not earth-mode Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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: 3039400cded24d4c4ecb1073 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) Hi Jacek, Roger, VLF, I have an idea: Am 04.02.2011 19:00, schrieb Jacek Lipkowski: > you would achieve much larger distances if you tried qrss with a > better matched antenna. you can try this with overhead powerlines in > rural areas too if you can fit your signal between the harmonics. long > phone lines work well too. What about a closed loop between two HV transmission line towers? These towers are grounded by a cable on the top of the towers (lightning strike protection). So there is no danger to operate here. One could try to place a VLF or LF(!) TX between two of these towers, building a closed loop. The loop current flows through the top wire of the towers and the signal might be radiated over a longer section of the system, like in a kind of gamma matched antenna. Roger/G3XBM could try this e.g. here: http://no.nonsense.ee/qthmap/?qth=JO02DG76TO&from=JO02DG76TB I see no danger in these experiments since the systems are grounded. Anyway there might be a current flow of some 10 A in that top wire. Maybe it is possible to extract some current (perhaps some 10 mA) in that loop and use a current transformer to build up the power supply for the TX? :-) Has someone tried that before? :-) 73, Stefan/DK7FC