Return-Path: Received: (qmail 13627 invoked from network); 17 Sep 1999 14:30:14 +0100 Received: from magnus.plus.net.uk (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 17 Sep 1999 14:30:14 +0100 Received: (qmail 11180 invoked from network); 17 Sep 1999 13:28:12 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by magnus.plus.net.uk with SMTP; 17 Sep 1999 13:28:12 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 11Rxu2-0008Nm-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 17 Sep 1999 14:18:14 +0100 Received: from mserv1c.u-net.net ([195.102.240.33]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 11Rxu2-0008Nh-00 for rsgb_lf_group@blacksheep.org; Fri, 17 Sep 1999 14:18:14 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: from rsgb.u-net.com ([195.102.80.225] helo=rsgb.org.uk) by mserv1c.u-net.net with smtp (Exim 2.10 #34) id 11Rymu-0003x3-00 for rsgb_lf_group@blacksheep.org; Fri, 17 Sep 1999 14:14:57 +0000 Received: from miked by rsgb.org.uk with SMTP (MDaemon.v2.7.SP5.R) for ; Fri, 17 Sep 1999 14:04:33 +0100 From: "Mike Dennison" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Organization: Radio Society of Great Britain To: rsgb_lf_group@blacksheep.org Date: Fri, 17 Sep 1999 14:04:31 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: LF: LF-antenna with top load In-reply-to: <004201bf0106$90ec4ca0$1696b38f@w8k3f0> X-Mailer: Pegasus Mail for Win32 (v3.11) X-MDaemon-Deliver-To: rsgb_lf_group@blacksheep.org X-Return-Path: miked@mail.rsgbhq Message-ID: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: PA0SE wrote: > Refering to the last part of my second report (16.9.99 14.17) it is clear > that top loads are hardly a substitute for height. Even raising the > antenna from 10 to 15 m increases radiation resistance more than even the > largest top load can do. This is easily understood as radiation resistance > is proportional to height squared whereas the most a top load can do is > doubling the radiation resistance. > Ah, but that's EFFECTIVE height squared, and one effect of the top load is to increase effective height by anything from 50% of actual height (no top load) to 100% (quarter-wave top load). Are you really saying that a 15m vertical will outperform a 10m inverted-L with a 1000m top load? Why does a top load only double the radiation resistance? Isn't it a function of total length, whether vertical or horizontal? Mike, G3XDV (IO91VT) http://www.dennison.demon.co.uk/activity.htm