Return-Path: Received: from rly-mg05.mx.aol.com (rly-mg05.mail.aol.com [172.20.83.111]) by air-mg02.mail.aol.com (v121.5) with ESMTP id MAILINMG021-a1248847c3b4f; Mon, 21 Jul 2008 08:08:41 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mg05.mx.aol.com (v121.5) with ESMTP id MAILRELAYINMG054-a1248847c3b4f; Mon, 21 Jul 2008 08:08:31 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1KKuBT-0004qb-Qd for rs_out_1@blacksheep.org; Mon, 21 Jul 2008 13:08:07 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1KKuBR-0004qS-9Q for rsgb_lf_group@blacksheep.org; Mon, 21 Jul 2008 13:08:05 +0100 Received: from smtpout18.attiva.biz ([85.37.16.20]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1KKuBO-00025N-Gr for rsgb_lf_group@blacksheep.org; Mon, 21 Jul 2008 13:08:05 +0100 Received: from FBCMFE02B20.fbc.local ([192.168.31.245]) by smtpout18.attiva.biz with Microsoft SMTPSVC(6.0.3790.1830); Mon, 21 Jul 2008 14:07:55 +0200 Received: from imac1.spineletronic2.191.it ([87.24.41.185]) by FBCMFE02B20.fbc.local with Microsoft SMTPSVC(6.0.3790.1830); Mon, 21 Jul 2008 14:07:54 +0200 X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9 Date: Mon, 21 Jul 2008 14:07:53 +0200 To: rsgb_lf_group@blacksheep.org From: Marco IK1ODO -2 In-Reply-To: References: Mime-Version: 1.0 Message-ID: X-OriginalArrivalTime: 21 Jul 2008 12:07:54.0727 (UTC) FILETIME=[6812B770:01C8EB2A] X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Loop Conundrum Content-Type: text/plain; charset="us-ascii"; format=flowed 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=none 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-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_helo : n X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : n At 13.29 21/07/2008, you wrote: >Was pondering this while out walking the other day, and couldn't come >to a satisfactory conclusion either way... > >A small magnetic loop mounted vertically has a defined radiation >resistance that is a function of its diameter, a loss that is function >of its conductor and hence a loss or efficiency that is the ratio of >the two. It is resonated with a good quality vacuum capacitor, and >fed/matched by any suitable metrhod. Lets also leave aside all the >myth and folklore about small loops, and also ignore the environment >for now. It also as a radiation pattern with nulls. > >Now, I take two identical such loops and mount then on the same centre >line but at right angles to eachother so there should be no coupling >between them, whatsoever. Now, I connect the two loops in series and >resonate the combination with a single capacitor of half the original >value. The resulting radiation pattern should have the nulls filled >in, and be a reasonable approximation to omnidirectional in azimuth. > >BUT... >What is the resulting change in efficiency? Andy, just my 2 cents: you have two magnetic fields in phase, that sum as vectors. So, from a distance you see only one vector, sum of the two, with nulls and so on; and you sum the areas of the two loops, projected on the plane orthogonal to the vector. If the loops are orthogonal between them you have a 1.41 times the effective area, and two times the resistance. The radiation pattern is not omnidirectional at all, and the total efficiency decreases. This is an intuitive reasoning... not scientific, HI. 73 - Marco IK1ODO / AI4YF