Return-Path: Received: from mtain-dl12.r1000.mx.aol.com (mtain-dl12.r1000.mx.aol.com [172.29.74.218]) by air-db08.mail.aol.com (v129.4) with ESMTP id MAILINDB084-869c4d07cb59108; Tue, 14 Dec 2010 14:54:01 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl12.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8A5E438000114; Tue, 14 Dec 2010 14:53:57 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PSaw2-0003R1-Go for rs_out_1@blacksheep.org; Tue, 14 Dec 2010 19:53:18 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PSaw2-0003Qs-3c for rsgb_lf_group@blacksheep.org; Tue, 14 Dec 2010 19:53:18 +0000 Received: from filter02.i-online.fr ([195.200.78.9]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PSavX-0006cf-Ir for rsgb_lf_group@blacksheep.org; Tue, 14 Dec 2010 19:53:18 +0000 Received: from smtp.qtxt.dns-iol.com ([195.200.78.13]) by filter02.i-online.fr (IceWarp 10.0.7 (2010-02-10)) with ESMTP (SSL) id WFL44036 for ; Tue, 14 Dec 2010 20:49:36 +0100 Received: (qmail 25808 invoked by uid 507); 14 Dec 2010 20:49:46 +0100 Received: from unknown (HELO ?192.168.1.103?) (john.rabson@numeo.fr@217.67.155.178) by smtp.qtxt.dns-iol.com with SMTP; 14 Dec 2010 20:49:46 +0100 From: John Rabson Mime-Version: 1.0 (Apple Message framework v1082) Date: Tue, 14 Dec 2010 20:49:58 +0100 In-Reply-To: To: rsgb_lf_group@blacksheep.org References: <007901cb9bbf$2c223810$0401a8c0@xphd97xgq27nyf> Message-Id: <7D6F2B55-E6E5-40BC-A7CF-D910C2232C9B@numeo.fr> X-Mailer: Apple Mail (2.1082) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Content-Type: multipart/alternative; boundary=Apple-Mail-2-516386189 Subject: AOG antennas (was Re: LF: BODGE ANTENNAS) 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=HTML_MESSAGE 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: 3039ac1d4ada4d07cb55361d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --Apple-Mail-2-516386189 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On 14 Dec 2010, at 20:10CET, Roger Lapthorn wrote: > Mal, >=20 > Please, I make no magical claims for the earth electrode antenna I use.= All I say is that, in certain circumstances, it works rather better than= one might expect both on RX and TX on VLF/LF/MF. >=20 For cave-to-surface communications we have found that, in general, an eart= h electrode system is much better than a tuned loop. When we tried both= systems at Kingsdale Master Cave Valley Entrance (a standard CREG test= site) the earth current antenna gave a 32 dB greater signal at the surfac= e than did the loop. It all seems to depend on the geology. If the top layer of the overburden= is essentially organic, then the loop tends to give better results. We still do not have a theoretical explanation for all this, but it works. John F5VLF --Apple-Mail-2-516386189 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

On 14 Dec 2010= , at 20:10CET, Roger Lapthorn wrote:

Mal,

Please, I make no mag= ical claims for the earth electrode antenna I use. All I say is that, in= certain circumstances, it works rather better than one might expect both= on RX and TX on VLF/LF/MF.

For cave-to-surface commun= ications we have found that, in general, an earth electrode system is much= better than a tuned loop. When we tried both systems at Kingsdale= Master Cave Valley Entrance (a standard CREG test site) the earth= current antenna gave a 32 dB greater signal at the surface than did the= loop.

It all seems to depend on the geology. &nb= sp;If the top layer of the overburden is essentially organic, then the loo= p tends to give better results.

We still do not= have a theoretical explanation for all this, but it works.

John F5VLF

=3D --Apple-Mail-2-516386189--