Return-Path: Received: (qmail 25121 invoked from network); 25 Apr 2001 21:13:30 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 25 Apr 2001 21:13:30 -0000 Received: (qmail 3403 invoked from network); 25 Apr 2001 21:13:29 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 25 Apr 2001 21:13:29 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14sWUc-0002K6-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 25 Apr 2001 22:06:34 +0100 Received: from mta6-rme.xtra.co.nz ([203.96.92.19]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14sWUY-0002Jy-00 for rsgb_lf_group@blacksheep.org; Wed, 25 Apr 2001 22:06:31 +0100 Received: from xtr743187 ([202.27.178.85]) by mta6-rme.xtra.co.nz with SMTP id <20010425210531.RDLS996647.mta6-rme.xtra.co.nz@xtr743187> for ; Thu, 26 Apr 2001 09:05:31 +1200 Message-ID: <004701c0cdcb$aa592d00$aab51bca@xtr743187> From: "Vernall" To: rsgb_lf_group@blacksheep.org References: <001001c0cd8a$9c2ab780$02666ec3@cestag> Subject: LF: Re: Loop preamps Date: Thu, 26 Apr 2001 09:03:23 +1200 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 5.00.2919.6600 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: Hi all, A further point about frame loop (magnetic) receiving performance is that the near field is generally smaller than for a similar dimensioned (active) (electric) vertical whip antenna. If neighbourhood QRM is a nuisance, then a well-sited frame loop can generally outperform a well-sited active whip, with the difference being the near field pattern. As others have commented, the pre-amp noise figure is unlikely to show up as a limitation (relative to QRN and QRM). I have also found considerable mutual coupling between my top-loaded vertical transmitting antenna (when tuned) and any LF receiving antenna I have tried, anywhere within my suburban section. The near field of the tuned transmitting antenna goes far beyond my own boundary! The practical solution is to leave the vertical floating during LF receive. 73, Bob ZL2CA