Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id uBSLQWUt029938 for ; Wed, 28 Dec 2016 22:26:33 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cMLgP-0000rX-5R for rs_out_1@blacksheep.org; Wed, 28 Dec 2016 21:22:49 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cMLgO-0000rO-IV for rsgb_lf_group@blacksheep.org; Wed, 28 Dec 2016 21:22:48 +0000 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cMLgL-0005MN-U3 for rsgb_lf_group@blacksheep.org; Wed, 28 Dec 2016 21:22:47 +0000 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 7BB7B20B4E for ; Wed, 28 Dec 2016 22:22:45 +0100 (CET) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3tpm0j1W9tzyp1 for ; Wed, 28 Dec 2016 22:22:45 +0100 (CET) Message-ID: <58642D25.4010603@posteo.de> Date: Wed, 28 Dec 2016 22:22:45 +0100 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <15946ec0beb-6491-2396d@webprd-a52.mail.aol.com> <58641AFA.807@abelian.org> In-Reply-To: <58641AFA.807@abelian.org> X-Scan-Signature: fc152e7304849b9a177649b85aea9f41 Subject: Re: VLF: New coil for 8270 Hz Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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-Scanned-By: MIMEDefang 2.75 Status: O X-Status: X-Keywords: X-UID: 9983 Hi Paul, Am 28.12.2016 21:05, schrieb Paul Nicholson: > > Stefan, do you have measurements, dimensions, etc of your VLF > antenna? I believe it is a wire strung between two buildings? Sure. The wire is about 70m long and 30m above ground (average). The are only 2 small trees below the antenna. I estimated the effective height is 25m but since 2 years there are more buildings arround the antenna, which lower the radiation resistance. I calculated a simplified structure of the antenna for LF using EZNEC. Then i'm scaling down/up the radiation resistance based on that simulation. Additionally i am assuming a loss of 25% due to the small trees and buildings and the feeder which is about 3m long, having almost no radiation resistance. I can measure C ~ 480 pF. The wire is out of stainless steel with 10mm diameter (or 12?). You may find some more details in google maps. Ah, and the earth resistance is very (!) low on all bands (below 500 kHz, i never tested HF there). That's all i know. There are some more details which will affect the radiation resistance. My estimated radiation resistance on 2970 Hz is 70 uOhm. With 23W and 230 mA and 230 Ohm (DC) coil losses, the ground resistance is less than 200 Ohm on 8.27 kHz. I can measure the -3 dB bandwidth in the next test. But for determining the ERP, we only need the antenna current and radiation resistance of course... > > In a first test i measured 230 mA RF current and the > > power supply showed 0.94 A and 24.5 V. So that's just 23W > > including PA losses. > > Should I look for a signal in my recording? Thanks, that's not necessary at the moment. 73, Stefan > > -- > Paul Nicholson > -- >