Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: from mtain-dc01.r1000.mx.aol.com (mtain-dc01.r1000.mx.aol.com [172.29.64.129]) by air-mc02.mail.aol.com (v127_r1.1) with ESMTP id MAILINMC022-a8d44b8552ff39b; Wed, 24 Feb 2010 11:25:35 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 0F435380000BF; Wed, 24 Feb 2010 11:25:32 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NkK2E-00068n-Kp for rs_out_1@blacksheep.org; Wed, 24 Feb 2010 16:24:26 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NkK2E-00068e-8q for rsgb_lf_group@blacksheep.org; Wed, 24 Feb 2010 16:24:26 +0000 Received: from mhost02c.leeds.ac.uk ([129.11.76.154]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from <C.Trayner@leeds.ac.uk>) id 1NkK2C-0005WY-JT for rsgb_lf_group@blacksheep.org; Wed, 24 Feb 2010 16:24:26 +0000 Received: from APOLLO1.ds.leeds.ac.uk (apollo1.leeds.ac.uk [129.11.5.4]) by mhost02c.leeds.ac.uk (8.14.3/8.14.3) with ESMTP id o1OGOISS004104 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for <rsgb_lf_group@blacksheep.org>; Wed, 24 Feb 2010 16:24:18 GMT Received: from HERMES8.ds.leeds.ac.uk ([fe80::39ce:23e:d0b5:7e24]) by APOLLO1.ds.leeds.ac.uk ([129.11.5.4]) with mapi; Wed, 24 Feb 2010 16:23:41 +0000 From: Chris Trayner <C.Trayner@leeds.ac.uk> To: "'rsgb_lf_group@blacksheep.org'" <rsgb_lf_group@blacksheep.org> Date: Wed, 24 Feb 2010 16:23:39 +0000 Thread-Topic: AW: LF: VLF_8.79 kHz_grounding systems Thread-Index: Acq1XqJg4CXyh+C9Tj2B2DDkRM4PYQACgv9IAAEY8GA= Message-ID: <38F4A9873A5B474DB6FB337B1B69ABA12603EB2DBA@HERMES8.ds.leeds.ac.uk> References: <38A51B74B884D74083D7950AD0DD85E82A1B13@File-Server-HST.hst.e-technik.tu-darmstadt.de>,<Pine.LNX.3.95.1100224211136.267C-100000@noname.nodomain.nowhere> <BF4A524700075746A6467658DFC7102C1286AD406E@ICTS-S-EXC2-CA.luna.kuleuven.be> In-Reply-To: <BF4A524700075746A6467658DFC7102C1286AD406E@ICTS-S-EXC2-CA.luna.kuleuven.be> Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: RE: AW: LF: VLF_8.79 kHz_grounding systems Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable 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: 3039ac1d40814b8552fc6ad7 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Hi Rik and others, Thanks for your contribution. > if using a short vertical monopole antenna at 9kHz a ground loss of more= than 1000 Ohm seems quite realistic to me. "Ground loss" at my QTH:=20 500kHz =3D 35 Ohm 137kHz =3D 130 Ohm=20 Do you mean resistance in the strict sense, i.e. the resistive component= of impedance; or in the rough sense, i.e. the ratio between voltage and= current, which is actually the modulus of impedance? I ask because there are capacitance and capacitance-like effects in the gr= ound. If you are looking at (in effect) a resistance in series with a capa= citance, that could explain the 1/f effect.=20 Regards, Chris G4OKW PS - more details can be found in Keller, G.V. & Frishcknecht, F.C. / Elec= trical Methods in Geoprospecting / Pergamon (1966). See in particular chap= 1 - or probably skim it, as it is detailed and can get a bit boring. Pp.= 43-55 talk about these capacitive-like effects. The size of the 'capacita= nce' (capacitance, not its reactance!) even varies with frequency. If you= look at the graph on p.52 you may need to reach for a bottle of the stron= g stuff ;-) ----------------------- Dr Chris Trayner School of Electronic & Electrical Engineering, The University of Leeds, Leeds LS2 9JT, United Kingdom Tel: +44 113 34 32053 Fax: +44 113 34 32032