Return-Path: Received: (qmail 15396 invoked from network); 21 Oct 2002 19:31:20 -0000 Received: from murphys.services.quay.plus.net (212.159.14.225) by mailstore with SMTP; 21 Oct 2002 19:31:20 -0000 Received: (qmail 27547 invoked from network); 21 Oct 2002 19:32:43 -0000 Received: from post.thorcom.com (193.82.116.70) by murphys.services.quay.plus.net with SMTP; 21 Oct 2002 19:32:43 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 183iHl-0004wq-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 21 Oct 2002 20:32:21 +0100 Received: from [203.109.254.42] (helo=grunt2.ihug.co.nz) by post.thorcom.com with esmtp (Exim 4.10) id 183iHk-0004wh-00 for rsgb_lf_group@blacksheep.org; Mon, 21 Oct 2002 20:32:20 +0100 Received: from p6-max10.chc.ihug.co.nz (athlon) [203.173.226.6] by grunt2.ihug.co.nz with smtp (Exim 3.35 #1 (Debian)) id 183iHf-0001XX-00; Tue, 22 Oct 2002 08:32:15 +1300 Message-ID: <002a01c27938$960896f0$0101a8c0@athlon> From: "Dave Brown" To: rsgb_lf_group@blacksheep.org References: Date: Tue, 22 Oct 2002 08:32:21 +1300 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: RE: Re: Re: Ant Questions Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=0.2 required=5.0tests=QUOTED_EMAIL_TEXT,SPAM_PHRASE_02_03,USER_AGENT_OEversion=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Just going from memory here, but I think if the vertical height of the outer end of the active part (ie above the insulator) of the droopy radials is no lower than around 70% of the vertical height of the upwire, then very little efficiency is lost. If anyone has a copy of 'VLF Engineering' handy you could check the actual figure in the chapter on transmitting antennas. The number of droopy radials may figure in this as well. 73 Dave ZL3FJ ----- Original Message ----- From: "Ashlock,William" To: Sent: Tuesday, October 22, 2002 3:21 AM Subject: LF: RE: Re: Re: Ant Questions > Hi Geri, > > >>Do not be tempted to droop the ends of any top wires. > > >... I challenge that. My umbrella antenna 18m high with 5 pieces of > top-load > >radials sloping downwards (each about 7 m long) **works fine** > > It "works fine" to be sure, and it's possible that this is the only physical > shape possible for your surroundings, BUT did you verify that there is no > loss from drooping the top hat radials Vs not drooping the top hat radials? > My experience with many shapes of top hats is that it DOES reduce the > radiation measured in the far field. The theoretical explanation I have seen > is that the effective height is reduced due to the current foldback. > > Bill A > > > > _____________________________________________________________________ > This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com > >