Return-Path: Received: (qmail 26190 invoked from network); 18 Mar 2002 19:49:05 -0000 Received: from unknown (HELO warrior.services.quay.plus.net) (212.159.14.227) by exhibition.plus.net with SMTP; 18 Mar 2002 19:49:05 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 19402 invoked from network); 18 Mar 2002 19:48:53 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior.services.quay.plus.net with SMTP; 18 Mar 2002 19:48:53 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16n4TT-0007YW-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 18 Mar 2002 21:15:23 +0000 Received: from mail4.messagelabs.com ([212.125.75.12]) by post.thorcom.com with smtp (Exim 3.33 #2) id 16n4TS-0007YR-00 for rsgb_lf_group@blacksheep.org; Mon, 18 Mar 2002 21:15:22 +0000 X-VirusChecked: Checked Received: (qmail 17036 invoked from network); 18 Mar 2002 19:37:18 -0000 Received: from merimac.us.gases.boc.com (HELO merimac) (204.149.80.4) by server-16.tower-4.messagelabs.com with SMTP; 18 Mar 2002 19:37:18 -0000 Received: by EXC_WIL04 with Internet Mail Service (5.5.2653.19) id ; Mon, 18 Mar 2002 14:44:57 -0500 Message-ID: From: "Ashlock,William" To: rsgb_lf_group@blacksheep.org Subject: LF: RE: R: Loop Conductors and proximity effect Rdc Rac Date: Mon, 18 Mar 2002 14:28:38 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Cesare, Thank you for your timely proximity equation! I calculate the spacing required to keep the proximity loss at 10% for two #12 ga (2.0 mm) copper conductors to be 0.5 inches. The spacing required for #12 Litz wire would be almost 0 because the sq root terms at the right side, based on Rrf/Rdc (mostly skin effect), would be close to 0. Would appreciate a check of my math from anyone. Bill A -----Original Message----- From: cesare tagliabue [mailto:cestag@dada.it] Sent: Monday, March 18, 2002 1:06 PM To: rsgb_lf_group@blacksheep.org Subject: LF: R: Loop Conductors and proximity effect Rdc Rac Hello John I have found the Mesny's expression on an old university stenciled book where only the data were given, but some time ago, for purpose of include it in a program, I have elaborated an empiric expression that approximates sufficiently these data. That is: q = ( 1 + .95 d / D )^2 - .22 Best 73 to all Cesare Cesare Tagliabue I 5 TGC WW-Loc JN53PS e-mail: cestag@dada.it url: http://www.dadacasa.com/i5tgc -----Messaggio originale----- Da: john sexton < computernetworks@excite.com > A: rsgb_lf_group@blacksheep.org < rsgb_lf_group@blacksheep.org > Data: luned́ 18 marzo 2002 17.46 Oggetto: LF: Loop Conductors and proximity effect Rdc Rac Hi Paul, >From the interesting formula given by Cesare, the short answer to your question appears to be 1/2 inch. I tried to find out more about Mesny's expression from the Internet, but it looks like you have to buy the book. I wonder whether Cesare can be persuaded to tell us the formula that relates q to D/d? At a guess it appears to be logarithmic. The second formula can be simplified to Reff/Rrf = 1 + (q-1)*sqrt(1-Rdc/Rrf) When D/d = 9, q = 1 so the second term disappears and Reff = Rrf. 73, John, G4CNN _____ ********************************************************************* This footnote confirms that this e-mail message has been scanned for the presence of known computer viruses by the MessageLabs Virus Control Centre. However, it is still recommended that you use local virus scanning software to monitor for the presence of viruses. *********************************************************************