Return-Path: Received: from mtain-mi01.r1000.mx.aol.com (mtain-mi01.r1000.mail.aol.com [172.21.131.154]) by air-md04.mail.aol.com (v129.4) with ESMTP id MAILINMD041-8b804d836eee129; Fri, 18 Mar 2011 10:40:46 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mi01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 19042380001D1; Fri, 18 Mar 2011 10:40:38 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Q0aqG-0002bd-7h for rs_out_1@blacksheep.org; Fri, 18 Mar 2011 14:39:52 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Q0aqF-0002bO-AX for rsgb_lf_group@blacksheep.org; Fri, 18 Mar 2011 14:39:51 +0000 Received: from out1.ip01ir2.opaltelecom.net ([62.24.128.237]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Q0aqC-0008VY-R8 for rsgb_lf_group@blacksheep.org; Fri, 18 Mar 2011 14:39:51 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvMAANoLg01cEYbC/2dsb2JhbACUPgODdY02d8JUhWMEgXaOVoMN X-IronPort-AV: E=Sophos;i="4.63,205,1299456000"; d="scan'208,217";a="347101863" Received: from unknown (HELO xphd97xgq27nyf) ([92.17.134.194]) by out1.ip01ir2.opaltelecom.net with SMTP; 18 Mar 2011 14:39:42 +0000 Message-ID: <006301cbe57a$4e780390$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Fri, 18 Mar 2011 14:39:37 -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: Re: LF: Loop TX antennas at VLF? Content-Type: multipart/alternative; boundary="----=_NextPart_000_0060_01CBE57A.4E411510" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNSAFE,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: 3039400cdec94d836ee677f8 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0060_01CBE57A.4E411510 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Knowing when to not bother seems logical with small inefficient loops= on 9 khz g3kev ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Friday, March 18, 2011 2:24 PM Subject: Re: LF: Loop TX antennas at VLF? Here's an Excel S/S I did in the 73kHz days. Other people have upd= ated versions now, but it serves to get you into a region to design fr= om - or know when to not bother http://www.g4jnt.com/DownLoad/MAGLOOP.XLS Andy www.g4jnt.com =20 On 18 March 2011 14:09, Roger Lapthorn wro= te: 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 loo= p antenna in the garden?=20 It would certainly avoid the need for very very large matching coi= ls 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 encour= aging. Mind you, 9kHz is very much lower than 136kHz, so the radiation= resistance 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_0060_01CBE57A.4E411510 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Knowing when to not bother seems logical with= small=20 inefficient loops on 9 khz
g3kev
 
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Friday, March 18, 2011= 2:24=20 PM
Subject: Re: LF: Loop TX ante= nnas at=20 VLF?

Here's an Excel S/S I did in the 73kHz days.  = Other=20 people have updated versions now, but it serves to get you into= a region=20 to design from - or know when to not bother
 
Andy

 
On 18 March 2011 14:09, Roger Lapthorn <rog= erlapthorn@gmail.com>=20 wrote:
Just=20 wondering if anyone has done the maths to work out what sort of ER= P could be=20 expected at 8.97kHz with, say, 100W to a smallish loop antenna in= the=20 garden?

It would certainly avoid the need for very very la= rge=20 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 fr= om G3XIZ=20 with around 2uW, this could be useful with long stable carrier tra= nsmissions=20 of several hours. Most of us could run a loop with an area of 100s= q m. with=20 thickish wire in our gardens. A loop might also be more practical= for=20 portable operations perhaps with a triangle with one high=20 support.

Certainly my own results with WSPR at 136 and 500k= Hz with=20 just a few watts and quite thin wire and around 80sq m loop area= were=20 encouraging. Mind you, 9kHz is very much lower than 136kHz, so the= radiation=20 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/<= /A>
G3XBM=    GQRP=20 1678    ISWL=20 G11088

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