Return-Path: Received: (qmail 12643 invoked from network); 1 Oct 2001 08:10:45 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 1 Oct 2001 08:10:45 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 10194 invoked from network); 1 Oct 2001 08:08:31 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 1 Oct 2001 08:08:31 -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 15nxyv-0008JK-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 01 Oct 2001 08:59:17 +0100 Received: from public1.thorcom.com ([212.172.148.10] ident=root) by post.thorcom.com with esmtp (Exim 3.16 #2) id 15nxyu-0008JD-00 for rsgb_lf_group@blacksheep.org; Mon, 01 Oct 2001 08:59:16 +0100 Received: from mail.cc.kuleuven.ac.be ([134.58.10.6]) by public1.thorcom.com with esmtp (Exim 3.20 #1) id 15nxvU-0003Kd-00 for rsgb_lf_group@blacksheep.org; Mon, 01 Oct 2001 08:55:44 +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 JAA188516 for ; Mon, 1 Oct 2001 09:50:42 +0200 Message-ID: <3.0.1.16.20011001084908.2af76e6c@mail.cc.kuleuven.ac.be> X-Sender: pb623250@mail.cc.kuleuven.ac.be X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Date: Mon, 01 Oct 2001 08:49:08 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" Subject: Re: LF: Re.73KHz beacon In-reply-to: <001a01c148e2$565e1660$438f883e@g3aqc> 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: >However I am a bit confused here after reading Dicks comments on your >marathon tests,in which he mentions 2.62db gain for a monopole. If this is >correct then the loss due to the environment is 5.62db not 3db. Hello Laurie and the others, There seems to be a bit of confusion about the 'real ERP'. As far as I get it you have to multiply the calculated radiated power (from the formula P = I^2*R with R = radiation resistance and I = antenna current) with the antenna gain. The gain of a short vertical is 4.77dBi or 2.62dBd. So assuming you put 2A into an antenna with a radiation resistance of 0.05 Ohm, you will radiate a power of 200mW. If the antenna is a short monopole the (theoretical) ERP will be 366mW (ERP has a half-wave dipole as reference) and the EIRP will be even 600mW (EIRP has an isotropic antenna as reference). CCIR Rec. 561-2 further defines EMRP where an short vertical monopole is the reference, so in the above case you would have 200mW EMRP. All this values are a bit theoretical as measurements performed by several hams show that the real ERP in most cases is 3-6dB below the calculated ERP. CEPT/ERC Recommendation 62-01 E (Mainz 1997) says : "That the band 135.7-137.8 kHz may be used with a maximum e.r.p. of 1 Watt on a secondary basis by the Amateur Service in CEPT countries." So they take ERP as a reference what means that we can run 1W ERP = 1.64W EIRP = 0.547W EMRP. Assming that the real ERP for any 'amateur sized' antenna will be at least 3 to 6dB below the theoretical ERP the radiated power (based on P = i^2*R) will have to exceed 1 to 2 Watt before you will reach the 1W ERP limit. 73, Rik ON7YD