Return-Path: Received: (qmail 9961 invoked from network); 17 Sep 1999 01:21:24 +0100 Received: from magnet.plus.net.uk (HELO magnet.force9.net) (195.166.128.26) by guiness.force9.net with SMTP; 17 Sep 1999 01:21:24 +0100 Received: (qmail 6763 invoked from network); 17 Sep 1999 00:25:38 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by magnet.plus.net.uk with SMTP; 17 Sep 1999 00:25:38 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 11Rldc-0002PP-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 17 Sep 1999 01:12:28 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: from imo18.mx.aol.com ([198.81.17.8]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 11RldY-0002OI-00 for rsgb_lf_group@blacksheep.org; Fri, 17 Sep 1999 01:12:24 +0100 Received: from G0MRF@aol.com by imo18.mx.aol.com (mail_out_v22.4.) id lDQFa12557 (7989) for ; Thu, 16 Sep 1999 20:11:50 -0400 (EDT) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 From: G0MRF@aol.com Message-ID: Date: Thu, 16 Sep 1999 20:11:50 EDT Subject: Re: Fw: LF: LF-antenna with top load To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Mailer: AOL 4.0.i for Windows 95 sub 134 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: In a message dated 9/16/99 7:13:33 GMT Daylight Time, d.w.rollema@gironet.nl writes: << To All, As a answer to a question by Mike, G3XDV, I have sent the following e-mail to the reflector: >Mike, G3XDV wrote: > > >> 1. No top load >> Efficiency: 10.8% >> Hello Dick / group. I recently installed a small broadcast transmitter on 1350kHz which was licenced for a maximum antenna height of 10m. After some time we managed to get a 10m glassfibre mast errected with a small top capacity hat, inductive loading at the centre (Litz), together with an element of distributed loading in the top section between the loading coil and the top hat. When examined by the authorities the efficiency was around 7%. A rough calculation would suggest that the Rrad of a 10m vertical is no greater than 0.1R, on 136k. The computers perfect ground assumption could be affecting the ability to compare the effects of different arrangements for top loading. Is it EZNEC which has poor / Avg / good / perfect / ground models? 73 David. G0MRF