Return-Path: Received: (qmail 28349 invoked from network); 2 Oct 2001 08:45:43 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 2 Oct 2001 08:45:43 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 17915 invoked from network); 2 Oct 2001 08:44:26 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 2 Oct 2001 08:44:26 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 15oL5x-0005wj-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 02 Oct 2001 09:40:05 +0100 Received: from mail.cc.kuleuven.ac.be ([134.58.10.6]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 15oL5w-0005we-00 for rsgb_lf_group@blacksheep.org; Tue, 02 Oct 2001 09:40:04 +0100 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 KAA127240 for ; Tue, 2 Oct 2001 10:39:23 +0200 Message-ID: <3.0.1.16.20011002093749.2d4784e4@mail.cc.kuleuven.ac.be> X-Sender: pb623250@mail.cc.kuleuven.ac.be X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Date: Tue, 02 Oct 2001 09:37:49 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" Subject: Re: LF: Re: 73KHz beacon In-reply-to: <3BB89B8F.93507C9F@netscapeonline.co.uk> References: <3.0.1.16.20011001084908.2af76e6c@mail.cc.kuleuven.ac.be> <3.0.1.16.20011001105044.2d67661a@mail.cc.kuleuven.ac.be> <3.0.1.16.20011001130655.30f79622@mail.cc.kuleuven.ac.be> 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: Hello Mal, At 17:36 1/10/01 +0100, you wrote: >> Unfortunately there is no perfect ground and no lossless loading coil so in >> practice (on 136kHz) a longer antenna will outperform a shorter and the one > >What I have been saying all the time and I am glad you and others realize this >at LAST!!!! I (and probably all the others) have been understanding this all the time. It doesn't change anything on the fact that a lower antenna efficiency can be perfectly compensated by higher power. Remember that we are ERP limited (1 Watt). So if a 'big guy' has 40m high vertical with a lot of toploading (radiation resistance something like 0.5 Ohm) he will have to limit the antennacurrent to about 1.5 A in order not to exceed the 1W ERP limit (assuming 50 Ohm loss this means running only +/- 100 Watt). On the other hand can a 'little boy' who is damned to use a 10m wet string as antenna (radiation resistance only 0.008 Ohm) pump up the power until he achieves an antennacurrent of 11 A. That will probably take a few kW but at the end he will have also 1 Watt ERP. If he is running sufficient power the 'little boy' will be heard as loud as the 'big guy'. The last one will either have to accept this physical facts or have to exceed the 1 W ERP limit (and breaking the law) to overwhelm the 'little boy'. To make a long story short : having a big antenna is a great help to get to the 1 W ERP limit without needing a big PA, but within reasonable limits a smaller antenna can be compensated by running more power. That is the fun (or for some the frustration) due to the 1 Watt ERP limit. 73, Rik ON7YD