Return-Path: <majordom@post.thorcom.com> Received: (qmail 18754 invoked from network); 13 May 2001 14:34:26 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 13 May 2001 14:34:26 -0000 Received: (qmail 16023 invoked from network); 13 May 2001 14:33:54 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 13 May 2001 14:33:54 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14ywps-0003Jz-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 13 May 2001 15:27:04 +0100 Received: from smtp-1.visp.telinco.net ([212.1.130.1]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14ywpq-0003Ju-00 for rsgb_lf_group@blacksheep.org; Sun, 13 May 2001 15:27:03 +0100 Received: from [212.1.140.26] (helo=g4jnt) by smtp-1.visp.telinco.net with smtp (Exim 3.22 #1) id 14ywks-0008P9-00 for rsgb_lf_group@blacksheep.org; Sun, 13 May 2001 15:21:55 +0100 Message-ID: <000601c0dbb8$bc424920$1a8c01d4@g4jnt> From: "Andrew Talbot" <G4JNT@thersgb.net> To: rsgb_lf_group@blacksheep.org Subject: LF: Re: Radiation from loading coil causing difference in current at top and bottom? Date: Sun, 13 May 2001 15:26:43 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.1 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: <majordom@post.thorcom.com> But these harmonic currents will upset your readings somewhat - where on a scope trace is the RMS value of a) the total waveform and b) the fundamental ? The harmonic currents will obviously be out of phase with the harmonic voltage, and cannot exit the top of the coil so if they are indeed entering the coil base they must be completing their loop in the fields from the coil itself - the quadrature, non dissipative, H or E fields. Very little radiation field will be generated from such a small radiating element, even at harmonic frequencies. There is nothing special about the coils we use on LF - (except the amount of mystery they seem to generate) Andy G4JNT >The output voltage of the TX was somewhat distorted due to harmonics, >showing up as some ripple at the positive and negative peaks of the >trace but the zero crossings were at exactly the same points as the voltage >over the resistor. >Thus as far as can be judged from oscilloscope traces voltage and current >at the bottom end of the coil >Perhaps the statement in the article is not true, or not applicable for the >sort of coils we >use on LF? >Could that explain the succes of the helical antenna?