Return-Path: Received: from mtain-mj11.r1000.mx.aol.com (mtain-mj11.r1000.mail.aol.com [172.21.164.95]) by air-mb06.mail.aol.com (v129.4) with ESMTP id MAILINMB063-a7664c19b627377; Thu, 17 Jun 2010 01:44:08 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mj11.r1000.mx.aol.com (Internet Inbound) with ESMTP id 81B4D38001AE7; Thu, 17 Jun 2010 01:44:06 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OP7s4-0007SM-UD for rs_out_1@blacksheep.org; Thu, 17 Jun 2010 06:42:36 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OP7s4-0007SD-IK for rsgb_lf_group@blacksheep.org; Thu, 17 Jun 2010 06:42:36 +0100 Received: from imr-ma01.mx.aol.com ([64.12.206.39]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OP7s1-0005h7-M8 for rsgb_lf_group@blacksheep.org; Thu, 17 Jun 2010 06:42:36 +0100 Received: from mtaout-db06.r1000.mx.aol.com (mtaout-db06.r1000.mx.aol.com [172.29.51.198]) by imr-ma01.mx.aol.com (8.14.1/8.14.1) with ESMTP id o5H5gTv5018341 for ; Thu, 17 Jun 2010 01:42:29 -0400 Received: from White (g229225029.adsl.alicedsl.de [92.229.225.29]) by mtaout-db06.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id A1160E000150 for ; Thu, 17 Jun 2010 01:42:26 -0400 (EDT) Message-ID: From: "Markus Vester" To: References: Date: Thu, 17 Jun 2010 07:42:17 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Who needs antennas! - success with ground electrodes on 500kHz Content-Type: text/plain; charset="iso-8859-1" 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=0.1 required=5.0 tests=MISSING_OUTLOOK_NAME 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: 3039400c89b64c19b626617e X-AOL-IP: 193.82.116.20 Dear Roger, this is interesting! I wonder if you attempted to estimate ERP or antenna efficiency. A measurement of effective height (ie. volts per fieldstrength for RX, or sqrt (EMRP) per current for TX) could be used to calculate loop area and "effective depth" of the return current. You could also compare 540+ kHz or 198 kHz BC signal voltages with reference to a small nonresonant loop. Best 73, Markus (DF6NM) From: Roger Lapthorn Sent: Wednesday, June 16, 2010 9:10 PM To: rsgb_lf_group@blacksheep.org Subject: LF: Who needs antennas! - success with ground electrodes on 500kHz Well, I'm amazed. This evening I connected my 500kHz transverter straight to the two connections of my sub-9kHz grounded electrodes and TXed WSPR. No attempt was made to match anything on the assumption that the two electrodes system looked not too far from 50 ohms resistive as measured between 1-9kHz.. Pout from the IRF510 is around 5W. What happened? Three people copied me - M0BMU, G7NKS and M0JXM with reports between -21 and -28dB S/N. The wire to the furtherest ground rod is at most 20m long and most of the way it is 1.5m above ground. Once again, this must be acting as a pretty effective loop mostly within the ground. Screen grab of the WSPR log attached. So, if you live on clunchy chalk soils like me then don't worry too much about big antennas, :-) 73s Roger G3XBM