Return-Path: Received: from mtain-mb07.r1000.mx.aol.com (mtain-mb07.r1000.mx.aol.com [172.29.96.27]) by air-dc06.mail.aol.com (v129.4) with ESMTP id MAILINDC063-86524d07b841131; Tue, 14 Dec 2010 13:32:34 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mb07.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1EDF13800016E; Tue, 14 Dec 2010 13:32:32 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PSZfC-00018F-GV for rs_out_1@blacksheep.org; Tue, 14 Dec 2010 18:31:50 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PSZfB-000186-Ta for rsgb_lf_group@blacksheep.org; Tue, 14 Dec 2010 18:31:49 +0000 Received: from out1.ip03ir2.opaltelecom.net ([62.24.128.239]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PSZf9-0005xB-Ny for rsgb_lf_group@blacksheep.org; Tue, 14 Dec 2010 18:31:49 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AhYFALJGB01cEYSE/2dsb2JhbACRXAOGc4s+eMJDhUoEgWCMS4JY X-IronPort-AV: E=Sophos;i="4.59,343,1288569600"; d="scan'208,217";a="329824683" Received: from unknown (HELO xphd97xgq27nyf) ([92.17.132.132]) by out1.ip03ir2.opaltelecom.net with SMTP; 14 Dec 2010 18:31:40 +0000 Message-ID: <005e01cb9bbd$23fb3120$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <003801cb9ba6$f1974450$0401a8c0@xphd97xgq27nyf> Date: Tue, 14 Dec 2010 18:31:35 -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: Earth Mode Content-Type: multipart/alternative; boundary="----=_NextPart_000_005B_01CB9BBD.234F87D0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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: 3039ac1d601b4d07b83f250c X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_005B_01CB9BBD.234F87D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable But if I understand what you say the antenna is 4m above ground, slope= s up at 45 degs, what height ? then down agn to 4m. This is an Elevate= d antenna, I am still confused because my impression of an earth mode= antenna is that it should be flat on the ground !!!!!!! What you describe is a grounded loop antenna, then Stefan claims an ea= rth mode antenna but his is lying on the ground, two wires each 600 me= tres What is the DEFINATION of an earth mode antenna, it seems everyone is= using a different system and Claiming its an earth mode antenna I hope you see the point and is it any wonder I am sceptical=20 de mal/g3kev ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, December 14, 2010 5:30 PM Subject: Re: LF: Earth Mode Yes Mal, let me clarify my earth electrode system here.... a.. A 1m copper ground stake is in the ground at the far end of my= short back garden. =20 b.. A length of 1mm diameter wire comes vertically from the far el= ectrode for 4m then slopes upwards at about 45 degrees back to the hou= se (17m length) then vertically downwards 4m to the upstairs bedroom= window. At this point this wire is connected to the centre of 10m of= coax to the front of the house where my PC and PA are located (in the= shack).=20 c.. The outer of the coax is connected to the metal central heatin= g radiator (in effect the second electrode as this connects to the cop= per pipes grounded outside the front of the house) 20m from the rear= electrode.=20 d.. The only points of contact to ground are at each end. No matching has proved necessary on 136 and 500kHz where the PA has= a roughly 50 ohm output. On VLF I use a step-up audio transformer (fr= om the 2-4 ohms of the audio PA) and I select the secondary for maximu= m current in the earth electrode "loop". I measured the AC resistance= at between 40-60 ohms at audio frequencies but I have not checked the= impedance at 136/500kHz although the antenna is a low-Q system and ad= justing series capacitance at 136 and 500 does not alter the current= much. 73s Roger G3XBM On 14 December 2010 15:52, mal hamilton wrot= e: LF Although I am not intending to follow this persuit I am curious. The confusion arises over the layout of the wires and is not made= clear by anyone using the system as far as I know. Two wires get a mention. Are they laid out across the ground like= a dipole, random length and the far end earthed by an earth rod drive= n into the ground. or do the wires run in parallel and what distance apart and are the wires insulated, at the feed point how close are the wires= , is a transformer used to match the amplifier of around 8 Ohms output= to the wires and what impedence are the wires. are the wires lying on the ground or slightly elevated ? also there is reference to buried pipes, elec wires etc enhancing the= propagation properties of the signal but since this would be specific= to the particular location=20 it cannot be relied upon as a statistic for a serious study how th= e earth mode works As well as above there is a power consideration when trying to det= ermin how far the signal would be received. From information that I have the distance covered would be short,= however if in some cases the wires were slightly elevated above groun= d even by a metre this could be considered an elevated antenna. Could someone clarify all these ambiguites=20 I await some info de g3kev --=20 g3xbm-qrp.blogspot.com/ www.g3xbm.co.uk www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 ------=_NextPart_000_005B_01CB9BBD.234F87D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
But if I understand what you say the= antenna is 4m=20 above ground, slopes up at 45 degs, what height ? then down agn to 4m.= This is=20 an Elevated antenna,  I am still confused because my impression= of an earth=20 mode antenna is that it should be flat on the ground !!!!!!!
What you describe is a grounded loop= antenna, then=20 Stefan claims an earth mode antenna but his is lying on the ground, tw= o wires=20 each 600 metres
What is the DEFINATION of an earth mo= de antenna, it=20 seems everyone is using a different system and Claiming its an earth= mode=20 antenna
I hope you see the point and is it an= y wonder I am=20 sceptical
de mal/g3kev
 
----- Original Message -----
Sent: Tuesday, December 14,= 2010 5:30=20 PM
Subject: Re: LF: Earth Mode

Yes Mal, let me clarify my earth electrode system=20 here....
  • A 1m copper ground stake is in the ground at the far end of my= short=20 back garden. =20
  • A length of 1mm diameter wire comes vertically from the far el= ectrode=20 for 4m then slopes upwards at about 45 degrees back to the house= (17m=20 length) then vertically downwards 4m to the upstairs bedroom windo= w. At this=20 point this wire is connected to the centre of 10m of coax to the= front of=20 the house where my PC and PA are located (in the shack).=20
  • The outer of the coax is connected to the metal central heatin= g radiator=20 (in effect the second electrode as this connects to the copper pip= es=20 grounded outside the front of the house) 20m from the rear electro= de.=20
  • The only points of contact to ground are at each end.
    • =
No=20 matching has proved necessary on 136 and 500kHz where the PA has a= roughly 50=20 ohm output. On VLF I use a step-up audio transformer (from the 2-4= ohms of the=20 audio PA) and I select the secondary for maximum current in the eart= h=20 electrode "loop". I measured the AC resistance at between 40-60 ohms= at audio=20 frequencies but I have not checked the impedance at 136/500kHz altho= ugh the=20 antenna is a low-Q system and adjusting series capacitance at 136 an= d 500 does=20 not alter the current much.

73s
Roger G3XBM

On 14 December 2010 15:52, mal hamilton <g3kevmal@talktalk.net> wrote:
LF
Although I am not intending to fo= llow this=20 persuit I am curious.
The confusion arises over the lay= out of the=20 wires and is not made clear by anyone using the system as far= as I=20 know.
Two wires get a mention. Are they= laid out=20 across the ground like a dipole, random length and the far end ear= thed by an=20 earth rod driven into the ground.
or
do the wires run in parallel and= what distance=20 apart
and
are the wires insulated, at the= feed point how=20 close are the wires, is a transformer used to match the amplifier= of around=20 8 Ohms output to the wires and what impedence are the wires.
are the wires lying on the ground= or slightly=20 elevated ?
also
there is reference to buried pipe= s, elec wires=20 etc enhancing the propagation properties of the signal but since= this would=20 be specific to the particular location
it cannot be relied upon as a sta= tistic for a=20 serious study how the earth mode works
As well as above there is a power= consideration=20 when trying to determin how far the signal would be received.
From information that I have the= distance=20 covered would be short, however if in some cases the wires were sl= ightly=20 elevated above ground even by a metre this could be considere= d an=20 elevated antenna.
Could someone clarify all these= ambiguites=20
 
I await some info
de g3kev
 



--=20
g= 3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
www.youtube.com/user/g3xbm=
G3XBM =   GQRP 1678    ISWL=20 G11088
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