Return-Path: Received: (qmail 12649 invoked from network); 14 Nov 2002 17:38:09 -0000 Received: from mx.last.plus.net (212.159.3.230) by mailstore with SMTP; 14 Nov 2002 17:38:09 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 6132 invoked from network); 14 Nov 2002 15:19:45 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by mx.last.plus.net with SMTP; 14 Nov 2002 15:19:45 -0000 X-SQ: A X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18CLts-0001oJ-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 14 Nov 2002 15:27:24 +0000 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.10) id 18CLtr-0001oA-00 for rsgb_lf_group@blacksheep.org; Thu, 14 Nov 2002 15:27:23 +0000 Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 18CLVp-0007V1-00 for rsgb_lf_group@blacksheep.org; Thu, 14 Nov 2002 15:02:33 +0000 Received: from [147.197.232.252] (helo=rsch-15.herts.ac.uk) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 18CLVf-0006ns-00 for rsgb_lf_group@blacksheep.org; Thu, 14 Nov 2002 15:02:23 +0000 Message-ID: <5.1.0.14.0.20021114122702.00b10570@gemini.herts.ac.uk> X-Sender: mj9ar@gemini.herts.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Thu, 14 Nov 2002 15:02:22 +0000 To: rsgb_lf_group@blacksheep.org From: "James Moritz" In-reply-to: <3DD389EE.E34C64A9@snet.net> References: <3DD35969.30941.58250D@localhost> <004801c28bb7$b2c00580$015e89d9@jackie> MIME-Version: 1.0 X-MailScanner: No Virus detected Subject: Re: LF: Loop vs Marconi Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-0.4 required=5.0tests=DEAR_SOMEBODY,IN_REP_TO,REFERENCES,SPAM_PHRASE_00_01version=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Dear Jay, LF group, At 06:33 14/11/2002 -0500, you wrote: >Not sure, but I think you can prove this with a small receive loop while >nulling out a local broadcast station. Tilt the loop even slightly off >vertical and away goes your null in a hurry. Oh no it doesn't! I have tried this with an LF loop antenna - if you have the loop horizontal, it nulls out everything from all directions, including the QRN. It would appear there really is no vertical H field near the ground for the loop to pick up at LF. Pity really, you could use the horizontal loop as an omnidirectional RX antenna otherwise. If you do this experiment with a BC band radio, and you imagine a plane cutting through the TX and RX, so long as you keep the axis of the ferrite rod in this plane (ie. at right angles to the H field), there will be a null in the signal however much you tilt the axis of the rod. Try this experiment outdoors, away from metalwork and wires which can distort the fields and spoil the null. If what you suggest about the TX loop antenna were true, the same is true of an RX loop antenna. This would mean you would never get a null in skywave DX signals with a vertical loop if they arrive at an appreciable angle. Experience shows you usually do get a reasonable null. Cheers, Jim Moritz 73 de M0BMU