Return-Path: Received: from mtain-da09.r1000.mx.aol.com (mtain-da09.r1000.mx.aol.com [172.29.64.81]) by air-df02.mail.aol.com (v128.1) with ESMTP id MAILINDF024-5ee94bb48c53326; Thu, 01 Apr 2010 08:06:43 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-da09.r1000.mx.aol.com (Internet Inbound) with ESMTP id D791738000088; Thu, 1 Apr 2010 08:06:41 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NxJ9Q-0005tW-Vl for rs_out_1@blacksheep.org; Thu, 01 Apr 2010 13:05:32 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NxJ9Q-0005tL-Ii for rsgb_lf_group@blacksheep.org; Thu, 01 Apr 2010 13:05:32 +0100 Received: from n1b.bullet.mail.aue.yahoo.com ([124.108.96.250]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1NxJ9N-0005au-Cy for rsgb_lf_group@blacksheep.org; Thu, 01 Apr 2010 13:05:32 +0100 Received: from [124.108.96.171] by n1.bullet.mail.aue.yahoo.com with NNFMP; 01 Apr 2010 12:05:18 -0000 Received: from [124.108.96.186] by t2.bullet.mail.aue.yahoo.com with NNFMP; 01 Apr 2010 12:05:18 -0000 Received: from [127.0.0.1] by omp101.mail.aue.yahoo.com with NNFMP; 01 Apr 2010 12:05:18 -0000 X-Yahoo-Newman-Id: 520815.37083.bm@omp101.mail.aue.yahoo.com Received: (qmail 72785 invoked by uid 1000); 1 Apr 2010 12:05:18 -0000 Received: from 124.108.96.73 by rel109.mail.aue.yahoo.com with SMTP; Thu, 01 Apr 2010 05:05:18 -0700 Received: (qmail 81061 invoked from network); 1 Apr 2010 12:05:18 -0000 Received: from 222-155-38-61.jetstream.xtra.co.nz (mcalevey@222.155.38.61 with login) by smtp104.tnz.mail.aue.yahoo.com with SMTP; 01 Apr 2010 23:05:18 +1100 EST X-Yahoo-SMTP: 34.QytGswBBh3k5ptT3bTJumdCN3YGn1ghuQCBsqkE8- X-YMail-OSG: d_n.tIwVM1kM._oQvJzNi67BvO1HhmVkuOmT0JehM.42WPUN6uarhvSiPRt2wiEnRk7mKGJ_Zj8uYVGQlhAtUevv67t8ntTej1g6pGTQwvh3VcQjIIPDaOI1FsMqFym0KyhHDGFYDQ1Ut_FvAu0pPaamEgfWTRVfqK9d5ML57n1cjM1xOEZxJdgOhw3apuodAjNIbq6HCiGTEl0KeXpQ2PaJHhifd0p7VZlpes_gSCpQ8KFOwDAPqABnLOWwmAzJ8iaSf3yQOl3Skg-- X-Yahoo-Newman-Property: ymail-3 Message-ID: <841031C22EC944FEB2BB3E1DC237717E@acer3f31164f8b> From: "Mike McAlevey" To: References: <001d01cad190$aa92e590$0901a8c0@lark> Date: Fri, 2 Apr 2010 01:05:17 +1300 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Spam-Score: 3.4 (+++) X-Spam-Report: autolearn=disabled,FORGED_MUA_OUTLOOK=3.36,UNPARSEABLE_RELAY=0.001 Subject: LF: Re: Re: E-Field Probe calibration question 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=1.6 required=5.0 tests=FORGED_MUA_OUTLOOK 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: 3039ac1d40514bb48c5179f3 X-AOL-IP: 193.82.116.20 Hi Andy. I would go along with Alan's thinking. It's about the probe to reference voltage. I am not a scientist or "enjuneir" either but with a one square metre untuned loop you can't go far wrong. Mike ----- Original Message ----- From: "Alan Melia" To: Sent: Friday, April 02, 2010 12:44 AM Subject: LF: Re: E-Field Probe calibration question > Hi Andy maybe I dont read it right, but if that is an E-field probe it is > not a "dipole" The input capacitance senses the voltage at two points on > the > wavefront. The ground plane is, I believe, irrelevant. You just need > another > capacitance separated from the "probe" to reference to voltage to. See > Renato's balanced probe (www.vlf.it) In your case this is the car.....but > it could be the size of a dinky toy.The area of the wavefront intercepted > by > the probe or the ground reference does not affect the terminal > voltage.....as I see it.................of course I might just be wrong > cos > i am really a scientist not an enjuneir!! > :-)) > Alan > > ----- Original Message ----- > From: "Andy Talbot" > To: > Sent: Thursday, April 01, 2010 12:02 PM > Subject: LF: E-Field Probe calibration question > > >> I have a calibrated E Field antenna (Procomm AAC-1) with a quoted >> antenna-factor of 0.15V into 50 ohms when placed in a field of 1V/m, >> >> This is mounted in the centre of a car roof and fed via a bulkhead > connector >> to a calibrated measuring receiver inside the vehicle, which we can >> assume >> is a Faraday cage at LF, S0 my question is : How is the effective > height >> of the antenna changed? It was 0.15m - the specification said so - but >> this would have been over an infinite groundplane. Do I regard the body > of >> the car as being the other half of a dipole? In which case, at 1.5m it > adds >> 20dB to the received signal and makes a mockery of calibrated measurement > of >> the E-Field value.. >> >> Is it worth persuing this route, or better to stick to untuned loops for >> calibrated E-Field measurements at LF/MF? >> >> >> Andy >> www.g4jnt.com >> > >