Return-Path: Received: from mtain-dc01.r1000.mx.aol.com (mtain-dc01.r1000.mx.aol.com [172.29.64.129]) by air-mb06.mail.aol.com (v129.4) with ESMTP id MAILINMB062-a6ff4d836e3e73; Fri, 18 Mar 2011 10:37:50 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dc01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 0D64A38000086; Fri, 18 Mar 2011 10:37:48 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Q0anX-0002Vd-B1 for rs_out_1@blacksheep.org; Fri, 18 Mar 2011 14:37:03 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Q0anW-0002VU-SX for rsgb_lf_group@blacksheep.org; Fri, 18 Mar 2011 14:37:02 +0000 Received: from out1.ip02ir2.opaltelecom.net ([62.24.128.238]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Q0anT-0008TG-Se for rsgb_lf_group@blacksheep.org; Fri, 18 Mar 2011 14:37:02 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AnwBAHQKg01cEYbC/2dsb2JhbACUPgODdT+Md3fCTIVjBIF2jlaDDQ X-IronPort-AV: E=Sophos;i="4.63,205,1299456000"; d="scan'208,217";a="359252941" Received: from unknown (HELO xphd97xgq27nyf) ([92.17.134.194]) by out1.ip02ir2.opaltelecom.net with SMTP; 18 Mar 2011 14:36:53 +0000 Message-ID: <005701cbe579$ea1e5110$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Fri, 18 Mar 2011 14:36:48 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: Loop TX antennas at VLF? Content-Type: multipart/alternative; boundary="----=_NextPart_000_0054_01CBE579.E9C3D500" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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-sid: 3039ac1d40814d836e3c2969 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0054_01CBE579.E9C3D500 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Roger=20 We have gone beyond the few watts and uW stage and should now be think= ing about Kilowatts and at least mWatts erp. Several hundred watts and balloons or kites must be the next stage wit= h the intention of having two way QSO'S at reasonable speeds. G3KEV ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Friday, March 18, 2011 2:09 PM Subject: LF: Loop TX antennas at VLF? 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?=20 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 aro= und 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 pract= ical for portable operations perhaps with a triangle with one high sup= port. 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 encouragin= g. Mind you, 9kHz is very much lower than 136kHz, so the radiation res= istance would be tiny I assume.=20 73s Roger G3XBM --=20 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 ------=_NextPart_000_0054_01CBE579.E9C3D500 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Roger
We have gone beyond the few watts and uW stage= and should=20 now be thinking about Kilowatts and at least mWatts erp.
Several hundred watts and balloons or kites mu= st be the=20 next stage with the intention of having two way QSO'S at reasonable=20 speeds.
G3KEV
 
 
----- Original Message -----
Sent: Friday, March 18, 2011= 2:09=20 PM
Subject: LF: Loop TX antennas= at=20 VLF?

Just wondering if anyone has done the maths to work= out what=20 sort of ERP could be expected at 8.97kHz with, say, 100W to a smalli= sh loop=20 antenna in the garden?

It would certainly avoid the need for= very very=20 large matching coils and may be easier to engineer than a Marconi.= Even an=20 efficiency of -80dB would allow 1uW ERP and, judging by results from= G3XIZ=20 with around 2uW, this could be useful with long stable carrier trans= missions=20 of several hours. Most of us could run a loop with an area of 100sq= m. with=20 thickish wire in our gardens. A loop might also be more practical fo= r portable=20 operations perhaps with a triangle with one high support.

Cer= tainly my=20 own results with WSPR at 136 and 500kHz with just a few watts and qu= ite thin=20 wire and around 80sq m loop area were encouraging. Mind you, 9kHz is= very much=20 lower than 136kHz, so the radiation resistance would be tiny I assum= e.=20

73s
Roger G3XBM

--
http://g3xbm-qrp.b= logspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/
G3XBM   GQRP=20 1678    ISWL G11088
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