Return-Path: Received: from mtain-mh02.r1000.mx.aol.com (mtain-mh02.r1000.mx.aol.com [172.29.96.214]) by air-ma08.mail.aol.com (v129.4) with ESMTP id MAILINMA083-b5324c62b14839c; Wed, 11 Aug 2010 10:18:48 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mh02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5C94B380003AC; Wed, 11 Aug 2010 10:18:39 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OjC6r-0001fv-9v for rs_out_1@blacksheep.org; Wed, 11 Aug 2010 15:16:49 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OjC6q-0001fm-LP for rsgb_lf_group@blacksheep.org; Wed, 11 Aug 2010 15:16:48 +0100 Received: from cavuit02.kulnet.kuleuven.be ([134.58.240.44]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OjC6m-0002ST-VS for rsgb_lf_group@blacksheep.org; Wed, 11 Aug 2010 15:16:48 +0100 Received: from smtps01.kuleuven.be (smtpshost01.kulnet.kuleuven.be [134.58.240.74]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id E45AC51C00A for ; Wed, 11 Aug 2010 16:16:31 +0200 (CEST) Received: from ICTS-S-HUB-N4.luna.kuleuven.be (icts-s-hub-n4.luna.kuleuven.be [10.112.9.14]) by smtps01.kuleuven.be (Postfix) with ESMTP id C697231E702 for ; Wed, 11 Aug 2010 16:16:31 +0200 (CEST) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N4.luna.kuleuven.be ([10.112.9.14]) with mapi; Wed, 11 Aug 2010 16:16:32 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Wed, 11 Aug 2010 16:16:31 +0200 Thread-Topic: LF: Earth antenna Thread-Index: Acs5TgCfUvRnCng+QSaUXW3nSBkUlAAEJIbP Message-ID: References: <4C626E89.5020002@o2.ie> ,<4C629209.8060206@o2.ie> In-Reply-To: <4C629209.8060206@o2.ie> 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: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: RE: LF: Earth antenna Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C510AC52D84ICTSSEXC2CAlu_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNSAFE,HTML_MESSAGE,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-sid: 3039ac1d60d64c62b13f3374 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C510AC52D84ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Tony, measuring voltages on untuned antennas is "tricky", in particular with sma= ll electrical antennas (compared to the wavelength) as these tend to have= large reactive components. On 60kHz the L-antenna you described has a reactive component of about 100= 00 Ohm while the resistive part will be some 10's to some 100's Ohm (mostl= y loss resistance). So properly tuning the antenna will increase the RX vo= ltage by several S-points. Ground loop antennas on the other hand seem more broadband. Maybe that explains why they perform better at lower frequencies ( compare= d to the untuned L-antenna). Anyway, your L-antenna should perform well on 500kHz. 73, Rik ON7YD ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Tony [ei8jk@o2.ie] Verzonden: woensdag 11 augustus 2010 14:05 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: Earth antenna Hi Roger. The soil here is well drained peaty topsoil about 400mm - 500mm deep on a= mixture of slate and shale and although I am 500m from the sea, I am 75m= above the water. I have no idea what the electrical conductivity is but I imagine it's prob= ably lower in the winter when my windows get a covering of salt during sto= rms. It would be interesting to pick on one reliable ground wave transmiss= ion and monitor it through various weather conditions. It would also be in= teresting to see how it works lower in frequency (sub 50 KHz), which is so= mething that I will definitely look into. 73, Tony, EI8JK On 11/08/2010 11:32, Roger Lapthorn wrote: Thanks for this Tony. Do you know what sort of soil/rock you have beneath you there? Here I am= on relatively low conductivity chalk/clunch with clay a few miles to the= north west under fenland peat. If the earth electrode antenna is behaving as a loop (a debated theory) th= en it is most effective is the "loop in the ground" is as large as possibl= e, which would be the case with low conductivity soil/rocks underneath: th= e return path between electrodes would be forced to take a longer route de= eper into the ground. If the soil between the electrodes has good conducti= vity then the return current would flow directly making the effective loop= size small. In the last few days we've had a lot of rain here and the results on 500kH= z last night with the earth electrode antenna suggest the rain made little= difference to performance with reception several times by PA0A. This is= counter-intuitive to me, as I would have expected levels to be weaker if= the soil was wet (loop formed being smaller etc.). Of course it could hav= e been that the contact resistance of the earth probes was lower and overa= ll the two effects cancelled? Whatever the theory says, the earth electrode "antenna" has some mileage= especially when, like me, there is little space for large "in the air" an= tennas. Sure, a big vertical or large loop in the air would be better (I= think), but this is about experimenting and discovering the limits of pos= sibilities. Good luck and keep everyone posted if you do further tests. 73s Roger G3XBM On 11 August 2010 10:34, Tony > wrote: I have finally found the time to get some (radio) work done here and got= my 2nd tower finished and I erected an inverted L, 10m vertical and 30m= top rising to 15m at the far end. I still have the "earth antenna" which= is just a length of wire laying on the ground 80m long and terminated dir= ectly to an earth stake and laying roughly in the same direction as the to= p wire of the L . Comparing the two gave some very interesting results. 10 MHz CW L =3D S7 earth =3D S1 7 MHz CW L =3D S9 earth =3D S3 R. Bristol 1566 KHz L =3D 0 earth =3D S2 Donebach 153 KHz L =3D S6 earth =3D S8 DCF77 77.5 KHz L =3D S3 earth =3D S5 MSF 60 KHz L =3D S4 earth =3D S8 All very non-technical I know, neither antenna was matched or tuned in any= way and was all done about 13:00z. There was no noticeable difference in the noise level but when I tried it= before the earth antenna was very much quieter after dark. I will try and= repeat this tonight and see what the difference is then. Tony, EI8JK. -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --_000_BF4A524700075746A6467658DFC7102C510AC52D84ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hello Tony,
 
measuring voltages on untuned antenn= as is "tricky", in particular with small electrical antennas (co= mpared to the wavelength) as these tend to have large reactive components.=
On 60kHz the L-antenna you desc= ribed has a reactive component of about 10000 Ohm while the resistive part= will be some 10's to some 100's Ohm (mostly loss resistance). So properly= tuning the antenna will increase the RX voltage by several S-points. 
Ground loop antennas on the other ha= nd seem more broadband.
Maybe that explains why they perform= better at lower frequencies ( compared to the untuned L-antenna).<= /div>
 
Anyway, your L-antenna should perfor= m well on 500kHz.
 
73, Rik  ON7YD
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Tony= [ei8jk@o2.ie]
Verzonden: woensdag 11 augustus 2010 14:05
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Earth antenna

Hi Roger.

The soil here is well drained peaty topsoil about 400mm - 500mm deep on a= mixture of slate and shale and although I am 500m from the sea, I am 75m= above the water.
I have no idea what the electrical conductivity is but I imagine it's prob= ably lower in the winter when my windows get a covering of salt during sto= rms. It would be interesting to pick on one reliable ground wave transmiss= ion and monitor it through various weather conditions. It would also be interesting to see how it works lowe= r in frequency (sub 50 KHz), which is something that I will definitely loo= k into.

73,
Tony, EI8JK


On 11/08/2010 11:32, Roger Lapthorn wrote:
Thanks for this Tony.

Do you know what sort of soil/rock you have beneath you there? Here I am= on relatively low conductivity chalk/clunch with clay a few miles to the= north west under fenland peat.

If the earth electrode antenna is behaving as a loop (a debated theory) th= en it is most effective is the "loop in the ground" is as large= as possible, which would be the case with low conductivity soil/rocks und= erneath: the return path between electrodes would be forced to take a longer route deeper into the ground. If the soil betw= een the electrodes has good conductivity then the return current would flo= w directly making the effective loop size small.

In the last few days we've had a lot of rain here and the results on 500kH= z last night with the earth electrode antenna suggest the rain made little= difference to performance with reception several times by PA0A. This is= counter-intuitive to me, as I would have expected levels to be weaker if the soil was wet (loop formed being= smaller etc.). Of course it could have been that the contact resistance= of the earth probes was lower and overall the two effects cancelled?

Whatever the theory says, the earth electrode "antenna" has some= mileage especially when, like me, there is little space for large "i= n the air" antennas. Sure, a big vertical or large loop in the air wo= uld be better (I think), but this is about experimenting and discovering the limits of possibilities.

Good luck and keep everyone posted if you do further tests.

73s
Roger G3XBM



On 11 August 2010 10:34, Tony <ei8jk@o2.ie> wrote:
 I have finally found the time to get some (radio) work done here and= got my 2nd tower finished and I erected an inverted L, 10m vertical and= 30m top rising to 15m at the far end. I still have the "earth antenn= a" which is just a length of wire laying on the ground 80m long and terminated directly to an earth stake and laying roug= hly in the same direction as the top wire of the L .
Comparing the two gave some very interesting results.

10 MHz  CW                L= =3D S7    earth =3D S1
7 MHz CW                   &n= bsp;L =3D S9    earth =3D S3
R. Bristol 1566 KHz    L =3D 0    earth =3D S2
Donebach 153 KHz    L =3D S6    earth =3D S8
DCF77 77.5 KHz        L =3D S3    earth =3D= S5
MSF 60 KHz                L =3D S4=    earth =3D S8

All very non-technical I know, neither antenna was matched or tuned in any= way and was all done about 13:00z.
There was no noticeable difference in the noise level but when I tried it= before the earth antenna was very much quieter after dark. I will try and= repeat this tonight and see what the difference is then.

Tony, EI8JK.




--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k
http://www= .youtube.com/user/g3xbm
G3XBM   GQRP 1678    ISWL G11088

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