Return-Path: Received: (qmail 2122 invoked from network); 15 Dec 2004 01:00:07 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 15 Dec 2004 01:00:07 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CeNZ8-000FA9-Of for dave@picks.force9.co.uk; Wed, 15 Dec 2004 01:02:57 +0000 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CeNZ8-000F9z-Ew for dave@picks.force9.co.uk; Wed, 15 Dec 2004 01:02:54 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1CeNVX-000B5r-Ph for dave@picks.force9.co.uk; Wed, 15 Dec 2004 00:59:11 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CeNUP-0004Eo-1d for rs_out_1@blacksheep.org; Wed, 15 Dec 2004 00:58:01 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CeNUO-0004Ef-K4 for rsgb_lf_group@blacksheep.org; Wed, 15 Dec 2004 00:58:00 +0000 Received: from smtp808.mail.ukl.yahoo.com ([217.12.12.198]) by relay.thorcom.net with smtp (Exim 4.41) id 1CeNUL-0007IG-5X for rsgb_lf_group@blacksheep.org; Wed, 15 Dec 2004 00:58:00 +0000 Received: from unknown (HELO w4o8m9) (james.moritz@btopenworld.com@81.131.95.10 with login) by smtp808.mail.ukl.yahoo.com with SMTP; 15 Dec 2004 00:57:50 -0000 Message-ID: <002301c4e240$e385d640$0a5f8351@w4o8m9> From: "James Moritz" To: rsgb_lf_group@blacksheep.org References: <5.1.0.14.0.20041213122834.022ec128@u0019445.kuleuven.be> Date: Wed, 15 Dec 2004 00:56:18 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 X-SPF-Result: relay.thorcom.net: 217.12.12.198 is neither permitted nor denied by domain of btopenworld.com X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=no,HTML_30_40=0.809,HTML_MESSAGE=0.001,RCVD_IN_SORBS=0.1 Subject: Re: LF: Hoar-Frost and Antenna Losses Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,HTML_MESSAGE 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-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit
Dear Rik, LF group,
 
 
----- Original Message -----
Sent: Monday, December 13, 2004 11:34 AM
Subject: Re: LF: Hoar-Frost and Antenna Losses

Hi Tom,

few weeks ago the item of wet wood in/near a loading coil was discussed and it seemed to increase the losses. But these would be "magnetic loss" while at the antenna it is the dielectric loss that counts.
 
 
I don't think so - bear in mind that the loading coil will be grounded at one end, and have the full antenna votage at the other, so as well as the magnetic field of the coil, there will also be an intense electric field. So the dielectric losses in the coil materials will also be very important.
 
BTW, the de-icing article is interesting - getting a 1m long "antenna" tuned up on 100kHz is quite impressive - they have used a set of ferrite-cored loading coils in series, immersed in oil to improve insulation. Allthough in spite of this, the Q of about 200 they got wasn't the best, and they seem to have had voltage breakdown problems, as you might expect. I wonder why they didn't use an air-cored loading coil?
 
Cheers, Jim Moritz
73 de M0BMU