Return-Path: Received: from mtain-dg03.r1000.mx.aol.com (mtain-dg03.r1000.mx.aol.com [172.29.65.11]) by air-dd10.mail.aol.com (v129.4) with ESMTP id MAILINDD103-86604d0786edd6; Tue, 14 Dec 2010 10:02:05 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dg03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 60A6B38000197; Tue, 14 Dec 2010 10:02:02 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PSWNP-0006dv-BB for rs_out_1@blacksheep.org; Tue, 14 Dec 2010 15:01:15 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PSWNO-0006dm-Gz for rsgb_lf_group@blacksheep.org; Tue, 14 Dec 2010 15:01:14 +0000 Received: from cavuit02.kulnet.kuleuven.be ([134.58.240.44]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PSWNK-0004HN-Uh for rsgb_lf_group@blacksheep.org; Tue, 14 Dec 2010 15:01:14 +0000 Received: from smtps01.kuleuven.be (smtpshost01.kulnet.kuleuven.be [134.58.240.74]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id 36B2475997A for ; Tue, 14 Dec 2010 16:01:00 +0100 (CET) Received: from ICTS-S-HUB-N1.luna.kuleuven.be (icts-s-hub-n1.luna.kuleuven.be [10.112.9.11]) by smtps01.kuleuven.be (Postfix) with ESMTP id 1DF6431E706 for ; Tue, 14 Dec 2010 16:01:00 +0100 (CET) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N1.luna.kuleuven.be ([10.112.9.11]) with mapi; Tue, 14 Dec 2010 16:01:00 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Tue, 14 Dec 2010 16:00:13 +0100 Thread-Topic: LF: Re: Re: G3XBM - very long carrier VLF transmission test Dec 15th Thread-Index: AcubnV2BrixTcaKBSAqNwcCfl8pl+QAAj8BT Message-ID: References: <612542AE1A3F497CB206279B0F0F8ECA@IBM7FFA209F07C> <001701cb9b95$a5dc1f10$0401a8c0@xphd97xgq27nyf>, In-Reply-To: Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,MAILTO_TO_SPAM_ADDR=0.276 Subject: RE: LF: Re: Re: G3XBM - very long carrier VLF transmission test Dec 15th Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C886FDD7537ICTSSEXC2CAlu_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE, MAILTO_TO_SPAM_ADDR,TO_ADDRESS_EQ_REAL 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: 3039ac1d410b4d0786ea368d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C886FDD7537ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Roger, have a look here : http://members.wideband.net.au/gzimmer/EarthComs/defaul= t.html 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Roger Lapthorn [rogerlapthorn@gmail.com] Verzonden: dinsdag 14 december 2010 15:41 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: Re: Re: G3XBM - very long carrier VLF transmission test= Dec 15th Chris/Mal et al, Certainly all my tests to date have been with what the US military calls= "earth mode". This is propagation through the ground primarily by conduct= ion and induction. What puzzles me, and some others, is that reception at= a distance of 1 to 5.6km has been better using a loop antenna at the RX= end rather than another pair of earth electrodes, suggesting the inductio= n field is the stronger component. I am not an electromagnetic theory man= and my physics is very rusty, so please excuse my ignorance here again. Mal is partly wrong about the use of earth electrodes. These have been use= d by the US military for VLF/ULF/ELF radiated communication with submarine= s worldwide. They have also been rejected as not secure enough for purely= through-the-ground communications between buried bunkers because of the= radiated component in the air! Where a very large "in the air" antenna structure is not practical, I susp= ect the results from an earth electrode are not that far down: on 136 and= 500kHz even my small 20m spaced earth electrode antenna is less than 8dB= down on the best "in the air" antenna I have so far managed to erect in= my tiny plot of land. My unanswered questions are: 1. Exactly what "helps" earth mode signals get as far as they do? I find= it amazing that just a few watts into my system is detected so well so fa= r away (5.6km best DX, but further is certainly possible in some direction= s yet to be checked). 2. How much signal is radiated in an earth mode set-up? With a signal that= is probably induced into overhead cables and conducted along miles of pip= ework and cables in the ground, railway tracks and even natural structures= like water courses and rocks, then surely a tiny proportion must be radia= ted. OK the radiated signal may be minuscule, but we have already seen tha= t with very slow QRSS and the power of Spectrum Lab and similar it is poss= ible to detect these weak signals at a considerable distance. The attenuat= ion of the radiated component is far less than the induction field compone= nt (6dB rather than 18dB attenuation for double distance I believe to a fi= rst order). Does anyone know how to calculate the amount of RF radiated in= an earth electrode antenna of given dimensions? 3. Assuming a very small amount of signal is radiated, what are the limits= for amateur communications using earth electrode structures? With 100-200= W and 600m long earth electrodes nearly 50km has already been achieved in= Germany. So, OK I'll be very lucky to be heard more than 10km away by anyone on Wed= nesday, but I have already been surprised many times on VLF/LF and it is= not totally beyond the bounds of possibility that, with QRSS6000 or simil= ar, detection at a moderate distance may be possible with a stable signal= source (mine is questionable I know) and suitable weak signal detection= techniques. I continue to promote earth electrodes because, for me, they have worked.= I do not deny that a large and well engineered vertical antenna would be= better, but for many of us this is simply not an option. Investigations, and the fun, continue... 73s Roger G3XBM On 14 December 2010 13:48, mal hamilton > wrote: Chris Generally speaking if you want to propagate a LF signal that covers hundre= ds of Kilometres use an elevated Aerial and a good ground system. The earth electrode TX and ground wires system is only intended for short= distances and received using the same method, howerver there will be RF= leakage and signals will also be copied at short distances using an elev= ated aerial but maybe copied further afield when the TX station is using= several hundred watts or Kilowatts. There is a lot of misleading and spectulative information about regarding= earth electrode antennas. What some are using for so called antennas I am= using as a ground for my elevated antennas. g3kev ----- Original Message ----- From: Chris To: rsgb_lf_group@blacksheep.org Sent: Tuesday, December 14, 2010 12:18 PM Subject: LF: Re: G3XBM - very long carrier VLF transmission test Dec 15th Hi Roger, I was under the impression that your earlier tests had shown that receptio= n from your earth electrodes at any distance was only possible by also usi= ng earth electrodes. This suggests that those of us using an aerial stand= little or no chance, correct? >From what I recall of tests done forty or so years ago with friends, using= wideband audio into the ground, any form of 'in air' reception attempt wa= s seriously bad. The reception of a signal injected into the earth as the= conduction medium also required the receive system to be in the same medi= um i.e. the earth. Do prove me wrong...and good luck with the tests. Vy 73, Chris, G4AYT, Whitstable, Kent. ----- Original Message ----- From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org ; Ni= ck Swales ; Chris Osborn ; Gary - G4WGT ; vlf0308@abelian.org<= mailto:vlf0308@abelian.org> ; paula.taylor@metoffice.gov.uk Sent: Sunday, December 12, 2010 10:51 PM Subject: LF: G3XBM - very long carrier VLF transmission test Dec 15th This Wednesday, Dec 15th, I will run tests on 8.7608kHz with very long con= tinuous TX periods of several hours interspersed with gaps of 0.5 to 1 hou= r. Transmissions will start at 0900GMT and finish at 2300GMT. I will revea= l the TX pattern after the test so the test is done "blind". I'd be most grateful if suitably equipped stations could look for any poss= ible signs of the signal, even though I shall only be using the 20m spaced= earth electrodes and 5W as used for my local earthmode tests. Those able= to screw the bandwidths right down may just be able to detect something,= although I think it is unlikely at any great distance. 15.12.10 0900-2300z 8.7608kHz Carrier "on" periods of 30mins or more Good luck to anyone having a go. 73s Roger G3XBM -- g3xbm-qrp.blogspot.com/ www.g3xbm.co.uk www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 -- g3xbm-qrp.blogspot.com/ www.g3xbm.co.uk www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --_000_BF4A524700075746A6467658DFC7102C886FDD7537ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hello Roger,
 
have a look here : http://members.wideband.net.au/gzimmer/EarthComs/default.html
 
73, Rik  ON7YD - OR7T
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Roger= Lapthorn [rogerlapthorn@gmail.com]
Verzonden: dinsdag 14 december 2010 15:41
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Re: Re: G3XBM - very long carrier VLF transmissi= on test Dec 15th

Chris/Mal et al,

Certainly all my tests to date have been with what the US military calls= "earth mode". This is propagation through the ground primarily= by conduction and induction. What puzzles me, and some others, is that re= ception at a distance of 1 to 5.6km has been better using a loop antenna at the RX end rather than another pair of earth elec= trodes, suggesting the induction field is the stronger component. I am not= an electromagnetic theory man and my physics is very rusty, so please exc= use my ignorance here again.

Mal is partly wrong about the use of earth electrodes. These have= been used by the US military for VLF/ULF/ELF radiated communication with submarines worldwide. They have also be= en rejected as not secure enough for purely through-the-ground communicati= ons between buried bunkers because of the radiated component in the air!

Where a very large "in the air" antenna structure is not practic= al, I suspect the results from an earth electrode are not that far down:= on 136 and 500kHz even my small 20m spaced earth electrode antenna is les= s than 8dB down on the best "in the air" antenna I have so far managed to erect in my tiny plot of land.

My unanswered questions are:

1. Exactly what "helps" eart= h mode signals get as far as they do? I find it amazing that just a fe= w watts into my system is detected so well so far away (5.6km best DX, but further is certainly possible in so= me directions yet to be checked).

2. How much signal is radiated in an earth mode set-up? With= a signal that is probably induced into overhead cables and conducted alon= g miles of pipework and cables in the ground, railway tracks and even natu= ral structures like water courses and rocks, then surely a tiny proportion must be radiated. OK the radi= ated signal may be minuscule, but we have already seen that with very slow= QRSS and the power of Spectrum Lab and similar it is possible to detect= these weak signals at a considerable distance. The attenuation of the radiated component is far less than the= induction field component (6dB rather than 18dB attenuation for double di= stance I believe to a first order). Does anyone know how to calculate the amount of RF radiated in= an earth electrode antenna of given dimensions?

3. Assuming a very small amount of signal is radiated, what are the lim= its for amateur communications using earth electrode structures? With= 100-200W and 600m long earth electrodes nearly 50km has already been achi= eved in Germany.

So, OK I'll be very lucky to be heard more than 10km away by anyone on Wed= nesday, but I have already been surprised many times on VLF/LF and it is= not totally beyond the bounds of possibility that, with QRSS6000 or simil= ar, detection at a moderate distance may be possible with a stable signal source (mine is questionable I know)= and suitable weak signal detection techniques.

I continue to promote earth electrodes because, for me, they have worked.= I do not deny that a large and well engineered vertical antenna would be= better, but for many of us this is simply not an option.

Investigations, and the fun, continue...

73s
Roger G3XBM



On 14 December 2010 13:48, mal hamilton <g3kevmal@talktalk.net>= wrote:
Chris
Generally speaking if you want to pro= pagate a LF signal that covers hundreds of Kilometres use an elevated Aeri= al and a good ground system.
The earth electrode TX and groun= d wires system is only intended for short distances and received=  using the same method, howerver there will be RF leakage and si= gnals will also be copied  at short distances using an elevated aerial but maybe copied further afield when the TX station is using= several hundred watts or Kilowatts.
 There is a lot of misleading an= d spectulative information about regarding earth electrode antennas. What= some are using for so called antennas I am using as a ground for my eleva= ted antennas.
g3kev
 
 
----- Original Message -----
From:= Chris
Sent: Tuesday, December 14, 2010 12= :18 PM
Subject: LF: Re: G3XBM - very long= carrier VLF transmission test Dec 15th

Hi Roger,
I was under the impression that your= earlier tests had shown that reception from your earth electrodes at any= distance was only possible by also using earth electrodes. This suggests= that those of us using an aerial stand little or no chance, correct?
From what I recall of tests done fort= y or so years ago with friends, using wideband audio into the ground, any= form of 'in air' reception attempt was seriously bad. The reception of a= signal injected into the earth as the conduction medium also required the receive system to be in the same medium i.e.&nbs= p;the earth.
Do prove me wrong...and good luck wit= h the tests.
Vy 73,
Chris, G4AYT, Whitstable, Kent.
----- Original Message -----
Sent: Sunday, December 12, 2010 10:= 51 PM
Subject: LF: G3XBM - very long carr= ier VLF transmission test Dec 15th

This Wednesday, Dec 15th, I will run tests on 8.7608kHz with very= long continuous TX periods of several hours interspersed with gaps of 0.5 to 1 hour. Transmission= s will start at 0900GMT and finish at 2300GMT. I will reveal the TX patter= n after the test so the test is done "blind".

I'd be most grateful if suitably equipped stations could look for any poss= ible signs of the signal, even though I shall only be using the 20m spaced= earth electrodes and 5W as used for my local earthmode tests. Those able= to screw the bandwidths right down may just be able to detect something, although I think it is unlikely at= any great distance.

15.12.10     <= br> 0900-2300z 
8.7608kHz   
Carrier "on" periods of 30mins or more

Good luck to anyone having a go.

73s
Roger G3XBM

--
g3xbm-qrp.blo= gspot.com/
www.g3xbm.co.uk www.youtub= e.com/user/g3xbm
G3XBM   GQR= P 1678    ISWL G11088



--
g3xbm-qrp.blo= gspot.com/
www.g3xbm.co.uk www.youtub= e.com/user/g3xbm
G3XBM   GQR= P 1678    ISWL G11088
--_000_BF4A524700075746A6467658DFC7102C886FDD7537ICTSSEXC2CAlu_--