Delivered-To: daveyxm@virginmedia.com Received: by 10.50.57.9 with SMTP id e9csp61516igq; Fri, 5 Jul 2013 06:38:09 -0700 (PDT) X-Received: by 10.14.241.136 with SMTP id g8mr11986148eer.104.1373031488914; Fri, 05 Jul 2013 06:38:08 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com. [195.171.43.25]) by mx.google.com with ESMTP id v1si6364649eeo.145.2013.07.05.06.38.08 for ; Fri, 05 Jul 2013 06:38:08 -0700 (PDT) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Uv5lK-0008AO-CE for rs_out_1@blacksheep.org; Fri, 05 Jul 2013 14:09:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Uv5lJ-0008AF-W0 for rsgb_lf_group@blacksheep.org; Fri, 05 Jul 2013 14:09:21 +0100 Received: from smtp-vbr4.xs4all.nl ([194.109.24.24]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Uv5lH-0002iU-Ns for rsgb_lf_group@blacksheep.org; Fri, 05 Jul 2013 14:09:20 +0100 Received: from pc-roelof (ndb.demon.nl [82.161.81.65]) by smtp-vbr4.xs4all.nl (8.13.8/8.13.8) with ESMTP id r65D9A8H089823 for ; Fri, 5 Jul 2013 15:09:19 +0200 (CEST) (envelope-from roelof@ndb.demon.nl) To: rsgb_lf_group@blacksheep.org References: <51D498BD.3050007@iup.uni-heidelberg.de> Date: Fri, 05 Jul 2013 15:09:06 +0200 MIME-Version: 1.0 From: "Roelof Bakker" Message-ID: In-Reply-To: <51D498BD.3050007@iup.uni-heidelberg.de> User-Agent: Opera Mail/12.15 (Win32) X-Virus-Scanned: by XS4ALL Virus Scanner X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hello all, Further to this discussion, I have done the ultimate test to demonstrate that an active whip antenna with a 1 meter long whip behaves as a capacitance at LF. For the test I used the ground wave carrier of semi local NDB ONO at 399.5 kHz. As it is the only station at that frequency the carrier level is very stable at daytime. The distance is 59 km, which excludes probably all skywave propagation. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [194.109.24.24 listed in list.dnswl.org] X-Scan-Signature: f38d515a9cad1e977fcfe251941a8120 Content-Type: text/plain; charset=iso-8859-15; format=flowed; delsp=yes Subject: Re: LF: VK1OD's analysis of the MiniWhip antenna 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 Status: O X-Status: X-Keywords: X-UID: 3137 Hello all, Further to this discussion, I have done the ultimate test to demonstrate that an active whip antenna with a 1 meter long whip behaves as a capacitance at LF. For the test I used the ground wave carrier of semi local NDB ONO at 399.5 kHz. As it is the only station at that frequency the carrier level is very stable at daytime. The distance is 59 km, which excludes probably all skywave propagation. The antenna was mounted vertical and the carrier of ONO produced a signal level of -69.1 dBm as received with a PERSEUS SDR. Next the antenna was mounted horizontal at the same height as the bottom of the vertical mount. This produce a signal level of -72.0 dBm. I reasoned that the mean height of the 1 meter long antenna when mounted vertical is 50 cm higher. So the antenna was then mounted horizontal 50 cm higher from its previous position. This produced a signal level of -69.9 dBm, close to the value measured when mounted vertical. The main point however, is that a horizontal polarized antenna should NOT receive a vertical polarized ground wave signal at (almost) the same strength. So at LF, there is nothing gained in using a whip instead of a small piece of copper clad PCB. Comments are much appreciated! Best regards, Roelof Bakker, pa0rdt