Return-Path: Received: from mtain-ma02.r1000.mx.aol.com (mtain-ma02.r1000.mx.aol.com [172.29.96.10]) by air-me01.mail.aol.com (v129.4) with ESMTP id MAILINME011-8ba04c42d8bb294; Sun, 18 Jul 2010 06:34:36 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5C66B380000A0; Sun, 18 Jul 2010 06:34:34 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OaRBg-0002oP-Ai for rs_out_1@blacksheep.org; Sun, 18 Jul 2010 11:33:36 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OaRBf-0002oG-PN for rsgb_lf_group@blacksheep.org; Sun, 18 Jul 2010 11:33:35 +0100 Received: from mhost02h.leeds.ac.uk ([129.11.77.151]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OaRBf-00010O-68 for rsgb_lf_group@blacksheep.org; Sun, 18 Jul 2010 11:33:35 +0100 Received: from APOLLO1.ds.leeds.ac.uk (apollo1.leeds.ac.uk [129.11.5.4]) by mhost02h.leeds.ac.uk (8.14.3/8.14.3) with ESMTP id o6IAXS2u020979 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for ; Sun, 18 Jul 2010 11:33:28 +0100 (BST) Received: from HERMES8.ds.leeds.ac.uk ([fe80::c078:16b5:73cf:6fbc]) by APOLLO1.ds.leeds.ac.uk ([129.11.5.4]) with mapi; Sun, 18 Jul 2010 11:33:28 +0100 From: Chris Trayner To: "rsgb_lf_group@blacksheep.org" Date: Sun, 18 Jul 2010 11:33:27 +0100 Thread-Topic: LF: EARTH MODE Thread-Index: AcsmZKjhYXQkAkgRTFuXgZxXa5QVuQ== Message-ID: <06EC7774-839A-4E75-835C-717830FE5963@leeds.ac.uk> References: <002401cb2662$106e5db0$0401a8c0@xphd97xgq27nyf> In-Reply-To: <002401cb2662$106e5db0$0401a8c0@xphd97xgq27nyf> Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: EARTH MODE Content-Type: text/plain; charset="us-ascii" 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=TO_ADDRESS_EQ_REAL 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: 3039ac1d600a4c42d8ba6c80 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) Hi Mal, Thanks for your comments. On 2010 Jul 18, at 11:14, mal hamilton wrote: > It would appear what some are using for antennas ie Earth Mode, I am usi= ng as a ground system for my Airborne antennas. > No wonder maximum tx range is very limited. A more straight forward appr= oach to cover the same distance would be a megaphone. However, we need to bear in mind that running two wires out to tent pegs= in the ground does more than give you a double Earth connection. They can= act as effective aerials. For their use in cave radio the propagation mec= hanism is still debated, but they can provide more than earth mode above= ground. When we were using them for cave radio in the West Riding some ye= ars ago, we picked up Finbar from Malin Head on 73kHz. That wouldn't have= been earth mode. Also, one of the problems with cave radio on 87kHz is th= at it suffers ACI from Loran, and the nearest Loran Txs are hundreds of km= away. 73, Chris G4OKW ----------------------- Dr Chris Trayner School of Electronic & Electrical Engineering, The University of Leeds, Leeds LS2 9JT, United Kingdom Tel: +44 113 34 32053 Fax: +44 113 34 32032