Return-Path: Received: (qmail 14200 invoked from network); 16 Jul 1999 09:43:30 +0100 Received: from magnet.plus.net.uk (HELO magnet.force9.net) (195.166.128.26) by guiness.force9.net with SMTP; 16 Jul 1999 09:43:30 +0100 Received: (qmail 5220 invoked from network); 16 Jul 1999 08:45:43 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by magnet.plus.net.uk with SMTP; 16 Jul 1999 08:45:43 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 1153Gk-0004mV-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 16 Jul 1999 09:22:58 +0100 Received: from mserv1b.u-net.net ([195.102.240.137]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 1153Gi-0004mP-00 for rsgb_lf_group@blacksheep.org; Fri, 16 Jul 1999 09:22:57 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: from rsgb.u-net.com ([195.102.80.225] helo=rsgb.org.uk) by mserv1b.u-net.net with smtp (Exim 2.10 #61) id 1153Fl-0001LV-00 for rsgb_lf_group@blacksheep.org; Fri, 16 Jul 1999 09:21:57 +0100 Received: from miked.rsgbhq [192.168.2.30] by rsgb.org.uk [192.168.2.132] with SMTP (MDaemon.v2.7.SP5.R) for ; Fri, 16 Jul 1999 09:17:13 +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, 16 Jul 1999 09:19:19 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 8bit Subject: LF: ERP X-Mailer: Pegasus Mail for Win32 (v3.01d) 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 Sender: Dick, PA0SE, and others have recently been using a multiplication factor of 1.83dB to obtain ERP. This is the supposed gain of a vertical antenna over a dipole because of ground reflection. Is this really vaild? Ground reflection surely must depend upon: (1) The efficiency of the local ground connection and (2) The conductivity of the ground both of which must have a much greater effect on the tiny (in terms of wavelength) antennas we use, than a full quarter-wave. Isn't the 1.83dB a theoretical improvement that is not achieved in practice? I am sure I would prefer to run a dipole on 136kHz, than a 14m vertical. Is this +1.83dB really useful at all? Or have I misunderstood? Mike, G3XDV (IO91VT) http://www.dennison.demon.co.uk/activity.htm