Return-Path: Received: from mtain-dj10.r1000.mx.aol.com (mtain-dj10.r1000.mail.aol.com [172.19.187.146]) by air-mb03.mail.aol.com (v127_r1.1) with ESMTP id MAILINMB033-a21e4b967890211; Tue, 09 Mar 2010 11:34:24 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dj10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 2CCD638000166; Tue, 9 Mar 2010 11:34:23 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Np2MO-0005JA-LP for rs_out_1@blacksheep.org; Tue, 09 Mar 2010 16:32:44 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Np2MO-0005J1-9K for rsgb_lf_group@blacksheep.org; Tue, 09 Mar 2010 16:32:44 +0000 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Np2MN-0003dx-It for rsgb_lf_group@blacksheep.org; Tue, 09 Mar 2010 16:32:44 +0000 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id o29GWe0q005288 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 9 Mar 2010 17:32:40 +0100 Received: from [129.206.29.99] (pc99.iup.uni-heidelberg.de [129.206.29.99]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id o29GWgUu004438 for ; Tue, 9 Mar 2010 17:32:42 +0100 Message-ID: <4B9678C3.7070907@iup.uni-heidelberg.de> Date: Tue, 09 Mar 2010 17:35:15 +0100 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.7) Gecko/20100111 Thunderbird/3.0.1 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <9afca2641003090337t4062bb3avc9b952612014c0ba@mail.gmail.com> In-Reply-To: <9afca2641003090337t4062bb3avc9b952612014c0ba@mail.gmail.com> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: LF: Possible VLF HV problems, or not? 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: 3039cdbc9d0f4b96788f59ac X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Dear LF, I have had some thoughts about HV problems when operating a vertical antenna wire at some 10kV. Normally, e.g. in a 50Hz system there will flow a current into the air (capacitive with a restistive component) due to the ionisation of the air when partial discharges occur. This is due to exceeding the maximum E field strange on the wire (a function of its radius and geometry and insulation and the gap between wire and insulation and the epsilon r of the insulation and and and ... ;-) ). In the special case of a VLF antenna there might be some special conditions that can limit the influence of the partial discharges. For example, the Z (sqrt (L/C) of such an antenna is very high, so the resonance is quickly lost if C is changing slightly. The presence of partial discharges will apparently increase the C since the surface is virtually increasing. There will be additional resistive losses but since a change the C will bring the circuit out of resonance (what would reduce the voltage at the wire), there might be a limitation of the momentary value of the voltage. This will be anything else than a stable process but there might be the effect, that the voltage will be limited like with a varistor or a spark gap in series with a resistor. So, theoretically, there will be many harmonics and my signal might be better visible at its harmonics than on the ground wave ;-) So, have some of you, perhaps on LF, have experiences with theese effects?? 73, Stefan/DK7FC