Return-Path: Received: (qmail 3457 invoked from network); 28 Nov 2002 11:53:27 -0000 Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 28 Nov 2002 11:53:27 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 25545 invoked by uid 10001); 28 Nov 2002 11:53:18 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 28 Nov 2002 11:53:18 -0000 X-SQ: A X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18HND2-0007QX-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 28 Nov 2002 11:51:56 +0000 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.10) id 18HND2-0007QO-00 for rsgb_lf_group@blacksheep.org; Thu, 28 Nov 2002 11:51:56 +0000 Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 18HNCC-0003pr-00 for rsgb_lf_group@blacksheep.org; Thu, 28 Nov 2002 11:51:04 +0000 Received: from [147.197.232.252] (helo=rsch-15.herts.ac.uk) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 18HNCA-0003Pv-00 for rsgb_lf_group@blacksheep.org; Thu, 28 Nov 2002 11:51:02 +0000 Message-ID: <5.1.0.14.0.20021128112913.00b01140@gemini.herts.ac.uk> X-Sender: mj9ar@gemini.herts.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Thu, 28 Nov 2002 11:50:06 +0000 To: rsgb_lf_group@blacksheep.org From: "James Moritz" In-reply-to: <3DE5B958.5738.32FCF@localhost> References: <5.1.0.14.0.20021125171906.00b9d028@pb623250.kuleuven.be> <001d01c29475$f77f6140$0500a8c0@charter.net> MIME-Version: 1.0 X-MailScanner: No Virus detected Subject: Re: LF: loop antenna Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-0.7 required=5.0tests=DEAR_SOMEBODY,IN_REP_TO,REFERENCES,SPAM_PHRASE_01_02version=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Dear Dave, Rik, LF Group, At 06:36 28/11/2002 +0000, you wrote: >I have just done a couple of calculations on Rik's loop using >formulae from Mike Underhill G3LHZ (which are quoted on my web site). >Mike says that the maximum Q is in fact limited by the size of the >loop and has a limiting value of Q=500/D, where D is the diameter of >the loop (or for a rectangular loop the circumference divided by pi). >Feeding Rik's dimensions into this gives a maximum Q of 20, and it >will in practice be lower than this due to resistive losses This calculation seems to be wildly divergent from the actual results of less than 1 ohm , amounting to a Q of a few hundred, quoted for "Lowfer" loops a little while back. Cheers, Jim Moritz 73 de M0BMU