Return-Path: Received: from mtain-dd05.r1000.mx.aol.com (mtain-dd05.r1000.mx.aol.com [172.29.64.145]) by air-me08.mail.aol.com (v129.4) with ESMTP id MAILINME083-8bbe4d8367f7da; Fri, 18 Mar 2011 10:11:03 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dd05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 15F08380000B1; Fri, 18 Mar 2011 10:11:00 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Q0aNR-00029Y-OH for rs_out_1@blacksheep.org; Fri, 18 Mar 2011 14:10:05 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Q0aNR-00029P-AF for rsgb_lf_group@blacksheep.org; Fri, 18 Mar 2011 14:10:05 +0000 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Q0aNO-0007tw-JH for rsgb_lf_group@blacksheep.org; Fri, 18 Mar 2011 14:10:05 +0000 Received: by iwr19 with SMTP id 19so5354649iwr.16 for ; Fri, 18 Mar 2011 07:09:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:date:message-id:subject:from:to :content-type; bh=QR2ATnEQ6JSmYj7Nuu057ArMbP8qThcdNhwJziBSb7k=; b=EopmeoU+bozfYHcMc6nvJDrxQvCz5cFcKRtCSBhQxif3DQcORxyABEO5uxxeqlyZos r0RnjTJpjHCpt9TMSZ+WzdBdqTwjtqXI9jdvIzD8hVOC5aF2KYAYRV4FKCTI/RLI8OPH G+BvTut2VowXLLGY+Z0H3gGFHJmzGQ6nHcwRY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; b=rd9Ge3h3df+WS8FDDEo2EEkYb/pCfGs5xF60KFwMZ2HRosZ/pRmaww3bwfp+P7K+OK 2luc9vOsgQ3i6XSjy925rrbxTvm9HNdKpt/cQTkoG+mRYt8iIevRBV5lvTUPbh0PK+6M 416+gP7Aogp1+IJO2JQxfOlTcybmTsTWsEwOs= MIME-Version: 1.0 Received: by 10.42.224.9 with SMTP id im9mr1518020icb.455.1300457396110; Fri, 18 Mar 2011 07:09:56 -0700 (PDT) Received: by 10.42.189.74 with HTTP; Fri, 18 Mar 2011 07:09:56 -0700 (PDT) Date: Fri, 18 Mar 2011 14:09:56 +0000 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Loop TX antennas at VLF? Content-Type: multipart/alternative; boundary=20cf30549f03240e7f049ec2550d 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=HTML_MESSAGE 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d008.1 ; domain : gmail.com DKIM : fail x-aol-sid: 3039ac1d40914d8367f41d65 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --20cf30549f03240e7f049ec2550d Content-Type: text/plain; charset=ISO-8859-1 Just wondering if anyone has done the maths to work out what sort of ERP could be expected at 8.97kHz with, say, 100W to a smallish loop antenna in the garden? It would certainly avoid the need for very very large matching coils and may be easier to engineer than a Marconi. Even an efficiency of -80dB would allow 1uW ERP and, judging by results from G3XIZ with around 2uW, this could be useful with long stable carrier transmissions of several hours. Most of us could run a loop with an area of 100sq m. with thickish wire in our gardens. A loop might also be more practical for portable operations perhaps with a triangle with one high support. Certainly my own results with WSPR at 136 and 500kHz with just a few watts and quite thin wire and around 80sq m loop area were encouraging. Mind you, 9kHz is very much lower than 136kHz, so the radiation resistance would be tiny I assume. 73s Roger G3XBM -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm https://sites.google.com/site/sub9khz/ G3XBM GQRP 1678 ISWL G11088 --20cf30549f03240e7f049ec2550d Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Just wondering if anyone has done the maths to work out what sort of ERP= could be expected at 8.97kHz with, say, 100W to a smallish loop antenna= in the garden?

It would certainly avoid the need for very very la= rge matching coils and may be easier to engineer than a Marconi. Even an= efficiency of -80dB would allow 1uW ERP and, judging by results from G3XI= Z with around 2uW, this could be useful with long stable carrier transmiss= ions of several hours. Most of us could run a loop with an area of 100sq= m. with thickish wire in our gardens. A loop might also be more practical= for portable operations perhaps with a triangle with one high support.
Certainly my own results with WSPR at 136 and 500kHz with just a few= watts and quite thin wire and around 80sq m loop area were encouraging.= Mind you, 9kHz is very much lower than 136kHz, so the radiation resistanc= e would be tiny I assume.

73s
Roger G3XBM

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http://g3xbm-qrp.blogspot.com/http://www.g3xbm.co= .uk
http://www= .youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/
G3XBM=A0=A0 GQRP 1678= =A0=A0=A0 ISWL G11088
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