Return-Path: Received: from mtain-ma02.r1000.mx.aol.com (mtain-ma02.r1000.mx.aol.com [172.29.96.10]) by air-dc10.mail.aol.com (v129.4) with ESMTP id MAILINDC104-86a84bd8a503351; Wed, 28 Apr 2010 17:13:39 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 10C4638000886; Wed, 28 Apr 2010 17:13:02 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1O7EXx-00040Y-S0 for rs_out_1@blacksheep.org; Wed, 28 Apr 2010 22:11:53 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1O7EXx-00040O-64 for rsgb_lf_group@blacksheep.org; Wed, 28 Apr 2010 22:11:53 +0100 Received: from 113-mo2-8.acn.waw.pl ([62.121.95.113] helo=paranoid.lipkowski.org) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1O7EXv-0000K2-EJ for rsgb_lf_group@blacksheep.org; Wed, 28 Apr 2010 22:11:53 +0100 Received: from paranoid.lipkowski.org (localhost [127.0.0.1]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id o3SLBokv005969 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 28 Apr 2010 23:11:50 +0200 Received: from localhost (sq5bpf@localhost) by paranoid.lipkowski.org (8.13.7/8.13.6/Submit) with ESMTP id o3SLBoPi005966 for ; Wed, 28 Apr 2010 23:11:50 +0200 X-Authentication-Warning: paranoid.lipkowski.org: sq5bpf owned process doing -bs Date: Wed, 28 Apr 2010 23:11:50 +0200 (CEST) From: Jacek Lipkowski To: rsgb_lf_group@blacksheep.org In-Reply-To: <4BD86B78.8000602@gmx.com> Message-ID: References: <003201cae3db$b7ffad50$0301a8c0@your91hoehfy9g>, <006e01cae6e3$2d46f4b0$4001a8c0@lark>, <4BD85BAD.18368.2436C56@dave.davesergeant.com> <4BD86B78.8000602@gmx.com> MIME-Version: 1.0 X-Spam-Score-sq5bpf: -2.601 () BAYES_00,SPF_HELO_PASS,SPF_PASS X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re: W1VLF 8.97 KHz UPDATE Trees, Questions, Ground Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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-aol-global-disposition: G x-aol-sid: 3039ac1d600a4bd8a4de3db8 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) On Wed, 28 Apr 2010, Mike.WE0H wrote: > Most people thought a TX loop would not radiate out of a backyard. a few years ago i've tested some very modest setups (no kilowatts and kilometers of wire). in a country area 1 km is certainly possible with a 4x14m loop made of pieces of 4mm2 and 1.5mm2 wire (if i remember correctly). the power was abt 40W and the matching was done via a capacitive divider. btw. 1km is more than my backyard :) you can also get 500m easily with a 1.5x2.5m 3-turn loop in a city area. > The calculations say a TX loop is a terrible antenna, but it does > radiate very well. yes and no. the calculations are correct in free space, however it has a very strong near-field, which will couple into anything that will conduct (powerlines, underground streams etc). thus if you're not in the cosmos, then in a realistic setting the antenna size is much greater. actually someone on this list called it "cheating" :) it's interesting that this cheating by law of recipriocity should increase the receive antenna size too. as mentioned above, with a very small loop i can do 500m in the city. this is probably because of all of the underground conductors here (powerlines, phone lines, catv etc). VY 73 Jacek / SQ5BPF