Return-Path: Received: (qmail 15689 invoked from network); 11 May 2001 13:50:17 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 11 May 2001 13:50:17 -0000 Received: (qmail 9652 invoked from network); 11 May 2001 13:49:46 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 11 May 2001 13:49:46 -0000 X-Priority: 3 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14yD2e-0000P2-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 11 May 2001 14:33:12 +0100 X-MSMail-Priority: Normal Received: from mail.cc.kuleuven.ac.be ([134.58.10.6]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14yD2a-0000Ot-00 for rsgb_lf_group@blacksheep.org; Fri, 11 May 2001 14:33:08 +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 PAA303178 for ; Fri, 11 May 2001 15:32:27 +0200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Message-ID: <3.0.1.16.20010511143329.21ffb3e6@mail.cc.kuleuven.ac.be> X-Sender: pb623250@mail.cc.kuleuven.ac.be X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Date: Fri, 11 May 2001 14:33:29 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" Subject: Re: LF: harmonics / LF antenna In-reply-to: <3.0.6.32.20010511091053.009224e0@pop.netspace.net.au> References: <3.0.1.16.20010510132736.2c87c87a@mail.cc.kuleuven.ac.be> <004401c0d92c$0f19a060$af6e74d5@w8k3f0> <65AECDF1F89AD411900400508BFC869F9C0491@pdw-mail-1.dera.gov.uk> <3AFA2E4C.EBB3C4EF@alg.demon.co.uk> 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: Hi Ric, In my calculations I assumed a perfect (capacitance free) coil. I found out that my 4.5mH loading coil has a self resonance just above 700kHz, so upward from there the reactance will drop rapidly (and will become capacitive). So it is very likely that a LF antenna can radiate very efficient on particular frequencies above 1MHz. It might not be a bad idea to have the harmonic radiation checked by another ham living 10-20km away. 73, Rik ON7YD At 09:10 11/05/01 +1000, you wrote: >G'day, > >Robert, AX2TAR, tried his switch mode LF transmitter without a low pass >filter. His 3rd harmonic was just visible on Argo, but his 19th harmonic >at about 3.3MHz was S9 here about 10km away. > >The 19th harmonic was probably where his wire was a halfwave long and >excited via the stray capacitance across his loading coil. > > > >73, Ric, VK7RO > > >