Return-Path: Received: (qmail 27090 invoked from network); 20 Nov 2002 13:32:57 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 20 Nov 2002 13:32:57 -0000 Received: (qmail 25809 invoked from network); 20 Nov 2002 10:35:49 -0000 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 20 Nov 2002 10:35:49 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18ESBm-0007pi-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 20 Nov 2002 10:34:34 +0000 Received: from [194.73.73.92] (helo=carbon.btinternet.com) by post.thorcom.com with esmtp (Exim 4.10) id 18ESBm-0007pZ-00 for rsgb_lf_group@blacksheep.org; Wed, 20 Nov 2002 10:34:34 +0000 Received: from host213-122-45-64.in-addr.btopenworld.com ([213.122.45.64] helo=main) by carbon.btinternet.com with smtp (Exim 3.22 #16) id 18ESBj-00029d-00 for rsgb_lf_group@blacksheep.org; Wed, 20 Nov 2002 10:34:33 +0000 Message-ID: <000701c29080$5c4c19a0$402d7ad5@main> From: "Alan Melia" To: "LF-Group" Date: Wed, 20 Nov 2002 10:32:29 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: re Spiral Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=1.6 required=5.0tests=SPAM_PHRASE_08_13,USER_AGENT_OEversion=2.42 X-Spam-Level: * Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Hi Steve, that sounds quite a beastie. we only got to 700 or so uH.....1.4mH top load sounds very interesting. I think the problem is that you will not get any help from "analysis" as most of the theoretical treatments dont seem to be able to deal with inductive top-load and the effect of increased top-capacitance on ground loss. My guess is that you will not see much more increase in Rrad now, but I cant judge what effect further development will have on the ground loss. You are certainly going the right way to judge from our experiments. The problem on ground loss is that the foot-print (as Laurie would call it) is defined by the sillouette of the spiral so doesnt really increase with the amount of wire used. Our ground loss only started to decrease when we put top-load wires out from the apex above the spiral but then "covering new ground". I suspect you will have to get the best you can with ground wires ("radials") probably earthed at the ends, like woulld be needed for a true vertical. You obviously will not need much inductance at the bottom to tune up to resonance. Are you able to make any measurements on the structure yet ?? This is a very interesting project. Cheers de Alan G3NYK alan.melia@btinternet.com