Return-Path: Received: from mtain-di11.r1000.mx.aol.com (mtain-di11.r1000.mx.aol.com [172.29.64.15]) by air-db09.mail.aol.com (v129.4) with ESMTP id MAILINDB093-864b4c3dc1e212b; Wed, 14 Jul 2010 09:55:46 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-di11.r1000.mx.aol.com (Internet Inbound) with ESMTP id 60C6B380000B5; Wed, 14 Jul 2010 09:55:35 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OZ2LA-0005fd-BN for rs_out_1@blacksheep.org; Wed, 14 Jul 2010 14:49:36 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OZ2L9-0005fU-G8 for rsgb_lf_group@blacksheep.org; Wed, 14 Jul 2010 14:49:35 +0100 Received: from smtp817.mail.ukl.yahoo.com ([217.12.12.246]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1OZ2L5-00037i-WF for rsgb_lf_group@blacksheep.org; Wed, 14 Jul 2010 14:49:35 +0100 Received: (qmail 90816 invoked from network); 14 Jul 2010 13:49:19 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=DKIM-Signature:Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=q+lQLIvfyHKtH5am0KJip6W1YrWYt0D/A/UWZAHzqltZjVz+8WFODgmmTzm8vXchTwb+iJLOryQZPZ9RIDsNk4xXfvK5gjYX7qiVL9S1nhGVv1GUd6pKSHrIwJHqgxNf7GUBbL7p1/gaX32zzQTVEDumDGxh/hem7aT9WT6H5/Y= ; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btopenworld.com; s=s1024; t=1279115359; bh=4D34Z15fZQYIm/OTOMAmnmmQmS+qAKVCre3C3Cw8gCQ=; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=EZI3kv2k2PMUSHm5bhiZ9Mvb1mr+zdCvi+vIhe2PXd/0GqQJDehdHizerSIA/G12VoOCQ/FLFTBKS4jDzBjrgXLWRy+9TvwOxzHu7x3F3v5hu/OMeY3NO9aF6M4w5i1qCfiT6XcztLNQ1uMQwNtC2fKkb0Tk8ppFtk3G3cc6TGs= Received: from JimPC (james.moritz@86.179.212.98 with login) by smtp817.mail.ukl.yahoo.com with SMTP; 14 Jul 2010 13:49:19 +0000 GMT X-Yahoo-SMTP: Cxhli3eswBD1ozmtAojhjrja86kWx0Qm9tycD5QR1DKWrOLgjJcXkw-- X-YMail-OSG: hacSFR8VM1m4X015RzJMfL8CjSiz.1Y8kozR_34ADi8WI_rfV0oaPT.dVblUjwT.8dNSOtwmS2TH1xmvyQTNjRI0zSQ88Sl53H87iXERxQ5kTZ6AoYmlZdWZMhoAWpcHTo8kYtyOBPE_WbXF6JAVIevTfrOin1GMms0qoklweCXTwbkIeoOaj0tGC3O1QnSHNOp2P4TktC1gXZEqhpiBPyDWMbp4862RmalrTzNmLRCKzJK31z2hNP_i7uWsrUQJ X-Yahoo-Newman-Property: ymail-3 Message-ID: <263121BD51374246B3F184A43B2E9619@JimPC> From: "James Moritz" To: References: <4C363DCD.303@iup.uni-heidelberg.de>,<4C3650A1.6040104@iup.uni-heidelberg.de> ,<4C3DA75D.80407@iup.uni-heidelberg.de> In-Reply-To: Date: Wed, 14 Jul 2010 14:49:19 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18197 DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,UNPARSEABLE_RELAY=0.001 Subject: LF: RE: DLF passive received with earth antenna Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d271.2 ; domain : btopenworld.com DKIM : fail x-aol-sid: 3039ac1d400f4c3dc1d72057 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none Dear Stefan, LF Group, The EMF induced in a small loop is: V = 2.1e-8 * fNAE f = frequency N = no. of turns A = area E = Electric field strength V/m (this assumes E/H = 377ohms, i.e. not near field) This will be the voltage you measure, assuming negligible loading. As Rik says, the ratio of voltages at a given frequency will be equal to the ratio of loop areas - this holds provided the loops are a small fraction of a wavelength in perimeter. With multi-turn loops, there may be errors caused by distributed capacitance, etc., but probably not a significant problem at VLF. Depending on the ground resistance and so on, this "earth antenna" might also act as an E-field antenna, or combined E-field / H-field antenna, like the K9AY and other "resistively terminated" loops. In this case, one would expect a different signal voltage at each end of the loop. Cheers, Jim Moritz 73 de M0BMU