Return-Path: Received: from rly-dc09.mx.aol.com (rly-dc09.mail.aol.com [172.19.136.38]) by air-dc05.mail.aol.com (v123.4) with ESMTP id MAILINDC052-b3d4a20732526d; Fri, 29 May 2009 19:43:43 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dc09.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDC091-b3d4a20732526d; Fri, 29 May 2009 19:43:34 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1MABim-0006kr-I6 for rs_out_1@blacksheep.org; Sat, 30 May 2009 00:42:44 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1MABim-0006ki-5z for rsgb_lf_group@blacksheep.org; Sat, 30 May 2009 00:42:44 +0100 Received: from mta21.charter.net ([216.33.127.81]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1MABij-0002lr-5v for rsgb_lf_group@blacksheep.org; Sat, 30 May 2009 00:42:43 +0100 Received: from imp10 ([10.20.200.10]) by mta21.charter.net (InterMail vM.7.09.01.00 201-2219-108-20080618) with ESMTP id <20090529234229.ZKYO3344.mta21.charter.net@imp10> for ; Fri, 29 May 2009 19:42:29 -0400 Received: from [192.168.0.2] ([66.189.74.84]) by imp10 with smtp.charter.net id xbiU1b00V1p78xe05biUen; Fri, 29 May 2009 19:42:29 -0400 Message-ID: <4A2072E4.40800@charter.net> Date: Fri, 29 May 2009 19:42:28 -0400 From: John Andrews User-Agent: Thunderbird 2.0.0.21 (Windows/20090302) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <20090529121437.120FDF3862@smtps02.kuleuven.be> <846AFC8AED804851AE6CA1E83B356E9F@JimPC> In-Reply-To: <846AFC8AED804851AE6CA1E83B356E9F@JimPC> X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re: modeling a loop Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Jim, Here is a little hard data which may be of some use. The antenna still exists in somewhat distorted form due to an ice storm last winter. Conductor height: 23 Meters Horizontal length: 51 Meters Perimeter approx. 147 Meters Conductor: Single 5.7 mm dia. stranded copper, plus plastic insulation. Lower conductor clearance above ground: 3 Meters, average. The ground here is made up of glacial droppings -- lots of rocks and boulders, with gravel and sand. Typical conductivity would be 1 mS/M. RF bridge measured impedances at 137 kHz showed a fairly constant +j213 Ohms reactance over a wide temperature range. Resistance varied from 1.7 Ohms in winter to 2.05 Ohms in summer, representing a temperature range from -4C to 23C. The impedances at 508 kHz were considerably higher, with about +j1100 Ohms reactance year-round, and a winter to summer resistance range of 52 to 62 Ohms. The perimeter of the loop is close to a quarter wave at this frequency, and the feed point is near the center of the baseline, if that's of any help. At 137 kHz, a number of far-field (>5 km) measurements in the pattern maxima showed about 1 watt ERP (not EIRP) for 400 watts into the antenna. No measurements were taken at 500 kHz, and the unfortunate events of last winter would prevent any direct comparison. Hope this might be of some help in the discussion. John, W1TAG