Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w85ARUYD002431 for ; Wed, 5 Sep 2018 12:27:33 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1fxUxB-00038r-P8 for rs_out_1@blacksheep.org; Wed, 05 Sep 2018 11:22:29 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1fxUxB-00038i-1O for rsgb_lf_group@blacksheep.org; Wed, 05 Sep 2018 11:22:29 +0100 Received: from rhcavuit03.kulnet.kuleuven.be ([2a02:2c40:0:c0::25:136]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1fxUx6-0002Kd-EN for rsgb_lf_group@blacksheep.org; Wed, 05 Sep 2018 11:22:27 +0100 X-KULeuven-Envelope-From: rik.strobbe@kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: 784C2120328.A455F X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-2.cc.kuleuven.be (icts-p-smtps-2e.kulnet.kuleuven.be [134.58.240.34]) by rhcavuit03.kulnet.kuleuven.be (Postfix) with ESMTP id 784C2120328 for ; Wed, 5 Sep 2018 12:22:08 +0200 (CEST) Received: from ICTS-S-EXMBX24.luna.kuleuven.be (icts-s-exmbx24.luna.kuleuven.be [10.112.11.59]) (using TLSv1.2 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by icts-p-smtps-2.cc.kuleuven.be (Postfix) with ESMTPS id 74F3D2003B for ; Wed, 5 Sep 2018 12:22:08 +0200 (CEST) Received: from ICTS-S-EXMBX27.luna.kuleuven.be (10.112.11.62) by ICTS-S-EXMBX24.luna.kuleuven.be (10.112.11.59) with Microsoft SMTP Server (TLS) id 15.0.1365.1; Wed, 5 Sep 2018 12:22:08 +0200 Received: from ICTS-S-EXMBX27.luna.kuleuven.be ([fe80::291a:cc4f:6953:698a]) by ICTS-S-EXMBX27.luna.kuleuven.be ([fe80::291a:cc4f:6953:698a%25]) with mapi id 15.00.1365.000; Wed, 5 Sep 2018 12:22:08 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Thread-Topic: R: LF: Antenna environment changes Thread-Index: AQHURPH1nn2w3zZnskyrshKlrmOct6ThOBuAgAAMBoCAADPsFA== Date: Wed, 5 Sep 2018 10:22:08 +0000 Message-ID: <1536142926551.20983@kuleuven.be> References: <165a8bb827e.marcocadeddu@tin.it> <5B8F9291.7090601@posteo.de>,<2f2c5632-b82a-91c7-3502-d88b7657d038@n1bug.com> In-Reply-To: <2f2c5632-b82a-91c7-3502-d88b7657d038@n1bug.com> Accept-Language: nl-BE, en-GB, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.112.50.1] MIME-Version: 1.0 X-Spam-Score: -0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Hi Paul, same here, losses are high in summer: up to 70 Ohm (475 kHz) or 180 Ohm (137 kHz). In winter it drops to 35 Ohm (475 kHz) and 120 Ohm (137kHz). I always assumed it was not so much affected the soil but rather by all the trees surrounding the antenna that loose their leaves and go to "sleep" in winter. Last february I raised the antenna from 12m to 14m in my attempt to get some extra ERP to cross the Atlantic and actually the losses increased slightly. I thought this was caused by the topload coming closer to some branches. But fortunately the overall effect was positive and we had our QSO ;-) [...] 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 [2a02:2c40:0:c0:0:0:25:136 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain X-Scan-Signature: ead411ce91f9601ce3974c7575797436 Subject: Re: R: LF: Antenna environment changes Content-Type: text/plain; charset="iso-8859-1" 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=TO_ADDRESS_EQ_REAL 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 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by klubnl.pl id w85ARUYD002431 Hi Paul, same here, losses are high in summer: up to 70 Ohm (475 kHz) or 180 Ohm (137 kHz). In winter it drops to 35 Ohm (475 kHz) and 120 Ohm (137kHz). I always assumed it was not so much affected the soil but rather by all the trees surrounding the antenna that loose their leaves and go to "sleep" in winter. Last february I raised the antenna from 12m to 14m in my attempt to get some extra ERP to cross the Atlantic and actually the losses increased slightly. I thought this was caused by the topload coming closer to some branches. But fortunately the overall effect was positive and we had our QSO ;-) 73, Rik ON7YD - OR7T ________________________________________ Van: owner-rsgb_lf_group@blacksheep.org namens N1BUG Verzonden: woensdag 5 september 2018 11:06 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: R: LF: Antenna environment changes Marco, ... a wingbeat of a butterfly... is very descriptive. I like it. :) Maybe with a sensitive detector I can use the LF antenna to count birds flying under it. :) Stefan, I have not seen any significant change in loss resistance during the summer. Rain, dry... hot, less hot... grass mowed or not mowed seem to have not much influence. My loss resistance in summer is very high. I need that aluminum foil! During the winter my loss resistance changed a lot with temperature. Colder = lower resistance. I did not understand what was changing. I do not think variations in temperature could affect the ground very much with 1m of snow over it but maybe I am wrong. Perhaps it was the snow itself changing with temperature, or maybe it was the nearby trees. 73, Paul On 09/05/2018 04:23 AM, DK7FC wrote: > Paul, > > did the LF loss resistance drop after mowing the grass? > Someone should try to roll out household aluminium foil completely > within a radius of the height of the antenna to see how it loweres the > losses :-) Not so expensive actually. > > 73, Stefan > > Am 05.09.2018 09:56, schrieb marcocadeddu@tin.it: >> .. a wingbeat of a butterfly.. >> >> be careful to move around the antenna and touch metal parts while >> transmitting Paul it is a very "reactive" area not only for the field >> strenght concept :-)) >> I guess that the pipe laying on the ground it is part of the ground >> itself (maybe improving it ) when you rise it from ground level and >> eventually connect to other existing metal parts you really make >> change in the environment of the antenna (it is like to tophat wires >> moving in the space when wind blows) >> >> 73, Marco IK1HSS >> >> ----Messaggio originale---- >> Da: paul@n1bug.com >> Data: 5-set-2018 1.09 >> A: "rsgb_lf_group@blacksheep.org", >> "rsgb_lf_group@yahoogroups.co.uk", >> "Discussion of the Lowfer (US, European, & UK) and MedFer >> bands" >> Ogg: LF: Antenna environment changes >> >> Subtitle: Be careful what you do in the vicinity of your LF antennas... >> >> I had a 14m length of aluminum tube (proposed 30 meter rotatable >> dipole) laying on the ground just under one end of the top hat of >> the LF antenna. Today I picked it up and moved it about 20 meters >> away. To get it off the ground for mowing, I ran it through the >> lattice of a short tower (9m) that is not at all under the LF top >> hat. I placed it about 2m above ground. This caused the LF antenna >> resonance to change so much I could not retune with the variometer! >> It was quite a large shift in resonant frequency. >> >> I then experimented with moving the piece of aluminum tube around. >> It seems I can lay it on the ground anywhere I want with no affect >> to the LF antenna. But put it one or two meters above ground >> connected to another tower or mast and the LF antenna is drastically >> changed. >> >> I must remember not to move any pieces of metal around while the >> beacon is active! :-) >> >> Paul