Return-Path: Received: (qmail 8978 invoked from network); 18 Jan 2001 12:47:53 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 18 Jan 2001 12:47:53 -0000 Received: (qmail 24745 invoked from network); 18 Jan 2001 12:42:16 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 18 Jan 2001 12:42:16 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from majordom by post.thorcom.com with local (Exim 3.16 #1) id 14JEIg-0000m2-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 18 Jan 2001 12:36:22 +0000 Received: from mail.cc.kuleuven.ac.be ([134.58.10.6]) by post.thorcom.com with esmtp (Exim 3.16 #1) id 14JEId-0000lw-00 for rsgb_lf_group@blacksheep.org; Thu, 18 Jan 2001 12:36:19 +0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from LCBD15.fys.kuleuven.ac.be (LCBD15.fys.kuleuven.ac.be [134.58.80.15]) by mail.cc.kuleuven.ac.be (8.9.3/8.9.0) with SMTP id NAA15298 for ; Thu, 18 Jan 2001 13:36:07 +0100 Message-ID: <3.0.1.16.20010118142719.33cf5a3e@mail.cc.kuleuven.ac.be> X-Sender: pb623250@mail.cc.kuleuven.ac.be X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Date: Thu, 18 Jan 2001 14:27:19 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" Subject: Re: LF: Caged Coils In-reply-to: <001901c0813b$9ae7a5e0$940b883e@default> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: At 10:15 18/01/01 -0000, G3KEV wrote: >... >The antenna loading coil is an integeral part of the actual antenna system >and needs to be placed UNCAGED under the antenna vertical for maximum >efficiency. >As I said before the loading coil unshielded at the base of a short vertical >also contributes to the radiating efficiency >... The radiation resistance of a multiturn loop is : Rs = 31200 x (n x F / L^2)^2 where Rs = radiation resistance, n = number of turns, F = loop area, L = wavelength. For my loadingcoil n = 120 and F = 0.04m^2, so at a wavelength of 2200m the radiation resistance will be about 30 nano-Ohm. Estimated radiation resistance of my inverted-L antenna is about 40 milli-Ohm. Shielding the coil (done properly - avoiding short circuit turns) would make my signal 0.000003dB weaker. 73, Rik ON7YD