Return-Path: Received: (qmail 12398 invoked from network); 21 Jul 2004 11:51:13 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore01.plus.net with SMTP; 21 Jul 2004 11:51:13 -0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1BnFdE-0004BO-MI for dave@picks.force9.co.uk; Wed, 21 Jul 2004 12:51:32 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1BnFct-000C7E-Ek for dave@picks.force9.co.uk; Wed, 21 Jul 2004 11:51:11 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1BnFcC-0000kK-Ee for rs_out_1@blacksheep.org; Wed, 21 Jul 2004 12:50:28 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1BnFcC-0000kB-1v for rsgb_lf_group@blacksheep.org; Wed, 21 Jul 2004 12:50:28 +0100 Received: from one.surfree.co.uk ([195.80.0.234]) by relay.thorcom.net with esmtp (Exim 4.34) id 1BnFc8-0006B5-1s for rsgb_lf_group@blacksheep.org; Wed, 21 Jul 2004 12:50:28 +0100 Received: from standalone ([212.248.140.2]) by one.surfree.co.uk (8.9.3/8.9.3) with SMTP id NAA14045 for ; Wed, 21 Jul 2004 13:48:12 +0100 Received: by localhost with Microsoft MAPI; Wed, 21 Jul 2004 12:47:02 +0100 Message-ID: <01C46F20.D1EF6420.actalbot@southsurf.com> From: Andy To: "'rsgb_lf_group@blacksheep.org'" Date: Wed, 21 Jul 2004 12:47:00 +0100 Importance: high X-Priority: 1 (Highest) Organization: UKNWN(UK) X-Mailer: Microsoft Internet E-mail/MAPI - 8.0.0.4211 MIME-Version: 1.0 X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=no,RCVD_IN_SORBS=0.1,X_PRIORITY_HIGH=0.516 Subject: RE: LF: Loops v Verticals Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.5 required=5.0 tests=X_PRIORITY_HIGH autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) I view of the continuing arguments about this issue, is there anyone who knows, or knows someone, with the mathmatical understanding of antenna theory as well as the common sense, to come up with a point at which loops will perform better than verticals, for given criteria. A useful criterion might be the same amount of copper (include loading coil) in the antenna system, or a given amount of ground area. Every parameter has to be taken into account so its far from trivial, but must be calculatable. It would certainly make a suitable task for a PhD thesis (Mike U.. are you there?) Any deep analysis was way beyond me, but in the early days of 73kHz when we had a proper LF band rather than this high frequency stuff above 100kHz, I did some some simplistic spreadsheets that did suggest that for VERY LARGE loops (many tens or 100s of metres in effective diameter) there was an advantage over electric antennas of similar size, but for anything that would fit in a typical garden E field won every time. If the loop could be made metres in diameter for example, or of Litz conductors to this diameter, then it copuld be made smaller for a given efficiency, but the total of amount copper actually increased. Then there comes a point where the loop is of the same dimensions as the vertical, so what mode is then radiating (Mike U, are you still there ?) etc etc. This was borne out by G2AKV in Canterbury who used a huge loop of bog standard mains cable, quite low down and draped thorough trees. He was the strongest signal on the band for a long time (unreceivable because of his chirp, but that's another story). Just making uninformed or sarky comments isn't going to solve anything. Andy G4JNT (still lurking on this reflector, but 100% on microwaves these days) -----Original Message----- From: Alexander S. Yurkov [SMTP:fitec@omskcity.com] Sent: 2004/07/21 16:04 To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Loops v Verticals On Tue, 20 Jul 2004, hamilton mal wrote: > For those that do not know. Research around Europe has shown that VERTICALS > are the only antennas suitable for Transmitting on LF. Loops are fine > for Receiving, little or large but the bigger the better. Who has ever > heard of a LF broadcasting station using loops for TX. > 73 de G3KEV Though loop has any advantage if there is very bad enviroment (trees, buildings e t.c.) Antenna of a broadcasting station always is plased in clear field. So there is no reason to use loop in this case in my opinion. 73 de RA9MB/Alex http://www.qsl.net/ra9mb