Return-Path: Received: from mtain-mc01.r1000.mx.aol.com (mtain-mc01.r1000.mx.aol.com [172.29.96.73]) by air-df08.mail.aol.com (v129.4) with ESMTP id MAILINDF083-5f004bfae47eed; Mon, 24 May 2010 16:41:34 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mc01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7955E38000819; Mon, 24 May 2010 16:41:32 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OGeRe-0006rQ-DD for rs_out_1@blacksheep.org; Mon, 24 May 2010 21:40:18 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OGeRd-0006rH-GO for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 21:40:17 +0100 Received: from cavuit01.kulnet.kuleuven.be ([134.58.240.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OGeRb-0008Fw-Jv for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 21:40:17 +0100 Received: from smtps02.kuleuven.be (smtpshost02.kulnet.kuleuven.be [134.58.240.75]) by cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id 365467B804A for ; Mon, 24 May 2010 22:40:08 +0200 (CEST) Received: from ICTS-S-HUB-N1.luna.kuleuven.be (icts-s-hub-n1.luna.kuleuven.be [10.112.9.11]) by smtps02.kuleuven.be (Postfix) with ESMTP id 0E605F3862 for ; Mon, 24 May 2010 22:40:08 +0200 (CEST) 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; Mon, 24 May 2010 22:40:08 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Mon, 24 May 2010 22:37:50 +0200 Thread-Topic: LF: AW: 8.97kHz - Near field and radiated signals? Thread-Index: Acr7gFBaMRKV04jOQ6qUaHFRxoeZnwAAKkZ1 Message-ID: References: <38A51B74B884D74083D7950AD0DD85E82A1C00@File-Server-HST.hst.e-technik.tu-darmstadt.de> <315092772.1763254.1274721526409.JavaMail.fmail@mwmweb035> , 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: 0.1 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TAG_EXIST_TBODY=0.126 Subject: RE: LF: AW: 8.97kHz - Near field and radiated signals? Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C5106464EE3ICTSSEXC2CAlu_" 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_MESSAGE, HTML_TAG_EXISTS_TBODY,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: 3039ac1d60494bfae47c4662 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C5106464EE3ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Roger, interesting. Did I read it correct that your transmit frequency is 1kHz instead of 9kHz= ? I gues that also ground antennas become more efficient at higher frequenci= es. How did you match the antenna ? 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: maandag 24 mei 2010 22:28 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: AW: 8.97kHz - Near field and radiated signals? Attached is a map showing how far I managed on 1kHz earth mode this evenin= g. Green is strong RS56 signals and orange is just copied RS33 signals, by= ear. TX power 4W + 20m base electrodes, RX 80cm loop. 73s Roger G3XBM On 24 May 2010 20:36, Roger Lapthorn > wrote: Thanks Horst. I'll try a Marconi antenna at some point, although my space is limited to= little more than the antenna I used on 500kHz (a top loaded 5m vertical). This evening I extended the TX electrode spacings by connecting one end to= the copper pipes in the house, almost doubling the effective TX baseline= to about 20m. With this, my "earth mode" signals were much stronger and= I was able to cover further than before in a "by ear" walk-about test aro= und the fields. Ultimate range tonight was 0.4kms using 4W (probably less= as the TDA2003 was hot and probably turning down the power) and receiving= on an 80cm loop. active HPF, small AF amp and crystal earpiece. Range wa= s limited by 50Hz mains hum and background sferic noise. I must try this= set-up with my HF up-converter and FT817 this week which has good rejecti= on of 50Hz (and its harmonics) mains hum and a narrow CW filter. 73s Roger G3XBM On 24 May 2010 18:18, Horst St=F6cker > wrote: Hello Roger, Dreamers, if we define near field as < 2 lambda we are talking about everything belo= w 60 km.With this distance I woul be extremely lucky. I also do "walkaround tests" near my garden. But I bet only in the flat fi= eld one can see what is possible with small antenna an without a big loadi= ng coil. Out from my garden I tried my 10h/20t Marconi as well as a 30m earth base.= The Marconi worked better, but not good enough. A TV transformer (must be= flyback of course) made it much better. But all the trees and houses are coupling the radiated signal to earth and= also the AATIS-RX is very much influenced by them. I also assume that the horinontal parts of a wire do the same. So only a= vertical should work. For operation in city environment smaller antennas at the roof top (old CB= antennas) will possibly work better than the bigger vertical in my garden= between trees and houses at ground level. It might be worth a test. One of the next tests will be with my gig earth base. I have collected abo= ut 800m of surplus wire. Possibly this is another way to even radiate more= then near field. But I would be very surprised it this was good for any= DX. I bet Stefans kite antenna will at least be the only way to DX operation.= Unfortunately this is just portable and just temporary. vy73 Horst DO1KHS/DI2AN ________________________________ Von: Roger Lapthorn > Gesendet: 24.05.2010 18:36:28 An: rsgb_lf_group@blacksheep.org Betreff: Re: LF: AW: 8.97kHz - Near field and radiated signals? Thank you for your fast reply Stefan. In answer to your questions: * Currently, my TX electrode spacing is 10m, which is the best I can ma= nage in my small garden. Both electrodes are as far away from the mains an= d other utility services as I can manage. * I have not tried /P transmit testing yet. * My nearest ham who will listen/look is 3kms away, but using beaconing= I am able to go out myself and see how far I can reach. This is what I ha= ve done so far, going out into the fields behind my house with electrode= pairs or a loop receiver. Best (by ear reception) DX is 0.35kms, but the= system has much scope for optimisation still. * The largest single turn loop I could erect in my garden would be abou= t 50-70 sq m (about 15m top and 4m-5m high). The longest antenna length wo= uld also be 15m horizontal with some vertical section(s) too. * The best DX targets are quite modest: I would like to exceed 1km init= ially with the TX power I currently have (around 4W). If I could reach G6A= LB in the next village 3kms away I would be delighted. If I got any furthe= r I would be both amazed and VERY happy! 73s Roger G3XBM 2010/5/24 Stefan Sch=E4fer > Hello Roger, For your ground electrodes, ground electrodes may be the best "antenna" in= some 10...10m. I'm not sure how to calculate field strengths but i just= know about the 1/d^3 dependency, so twice the distance means 8 times the= power for the same signal reception, in the near field. But it is the que= stion what are the electrodes since there is ever a coupling to the mains= earth and all the metallic stuff in regions where people are living so th= is dependency might not be valid in your tests. As mentioned here, you cou= ld benefit from these conductors... But if you want to reach more distance with an antenna of the same size (e= .g. of your garden)and the same power, you could try such a TV transformer= . Take a wire, as long as possible and as high as possible, and apply some= kV on it by this transformer. It can even be resonated by adjusting the= air gap between the both ferrite parts. That results in a maximum output= voltage and thus "ERP". At least this would be a good alternative to your= ground electrode tests. You could easily compare the reachable distances.= Here i would use a E field antenna for reception in the near field. How far is your next receiving amateur radio station away? And have you tr= ied to do such tests outside the village/city, just like Jim does it with= his loop antenna? This could allow you to increase the distance of your= reception. Here, space is not limited and you could try 2x10m, 2x50m, 2x1= 00m and so on and tell us the difference in the feed point impedance at va= rious frequencies and your ODX :-) Maybe i will also do some ground electr= ode tests in summer but i am still not sure. The complete receiver of Jim= is a really good idea to check the QRM situation at a given QTH. Probably= i will also buit his loop design for such tests... Would be interesing wh= at is the maximum distance for a CW reception of my transmitted signal (wi= th the kite antenna and 6mW ERP) ;-) I will also do some near field tests in this week, to compare the performa= nce of my 2 grabbers. This will be done here: http://www.google.de/maps?f= =3Dq&source=3Ds_q&hl=3Dde&geocode=3D&q=3Dheiligenberg+heidelberg&sll=3D47.= 820666,9.312449&sspn=3D0.106733,0.219383&g=3Dheiligenberg&ie=3DUTF8&hq=3D&= hnear=3DHeiligenberg&ll=3D49.419391,8.704101&spn=3D0.001616,0.003428&t=3Dh= &z=3D18 in about 1,8km distance to my grabbers. Power will also be below= 100W and the antenna wire will be mounted on a tower in abt 15m height.= I will transmit with this TV transformer on a 40m wire. Roger, what size is your garden? What is the maximum wire length that you= can apply and in which height? What is your goal (best DX, a reals QSO wi= th the next equipped station or just do some funny tests?) So, wish you fun and success with your experiments! 73, Stefan/DK7FC PS: What is your locator / QTH? -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 NEU: WEB.DE DSL f=FCr 19,99 EUR/mtl. und ohne Mindest-Laufz= eit! http://produkte.web.de/go/02/ -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --_000_BF4A524700075746A6467658DFC7102C5106464EE3ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hello Roger,
 
interesting.
Did I read it correct that your tran= smit frequency is 1kHz instead of 9kHz ?
I gues that also ground antennas bec= ome more efficient at higher frequencies.
How did you match the antenna ?
 
73, Rik  ON7YD - OR7T
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Roger= Lapthorn [rogerlapthorn@gmail.com]
Verzonden: maandag 24 mei 2010 22:28
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: AW: 8.97kHz - Near field and radiated signals?
Attached is a map showing how far I managed on 1kHz earth mode this= evening. Green is strong RS56 signals and orange is just copied RS33 sign= als, by ear. TX power 4W + 20m base electrodes, RX 80cm loop.

73s
Roger G3XBM

On 24 May 2010 20:36, Roger Lapthorn <rogerlapthorn@gmai= l.com> wrote:
Thanks Horst. 

I'll try a Marconi antenna at some point, although my space is limited to= little more than the antenna I used on 500kHz (a top loaded 5m vertical).

This evening I extended the TX electrode spacings by connecting one end to= the copper pipes in the house, almost doubling the effective TX baseline= to about 20m. With this, my "earth mode" signals were much stronger and I was able to cover further than before in a &quo= t;by ear" walk-about test around the fields.  Ultimate range ton= ight was 0.4kms using 4W (probably less as the TDA2003 was hot and probabl= y turning down the power) and receiving on an 80cm loop. active HPF, small AF amp and crystal earpiece.  Range was limi= ted by 50Hz mains hum and background sferic noise. I must try this set-up= with my HF up-converter and FT817 this week which has good rejection of= 50Hz  (and its harmonics) mains hum and a narrow CW filter.

73s
Roger G3XBM




On 24 May 2010 18:18, Horst St=F6cker <horst.stoecker@web.d= e> wrote:
Hello Roger, Dreamers,
if we define near field as < 2 lambda we are talking about everything= below 60 km.With this distance I woul be extremely lucky.
I also do "walkaround tests" near my garden. But I bet only in= the flat field one can see what is possible with small antenna an without= a big loading coil.
Out from my garden I tried my 10h/20t Marconi as well as a 30m earth base.= The Marconi worked better, but not good enough. A TV transformer (must be= flyback of course) made it much better.
But all the trees and houses are coupling the radiated signal to earth and= also the AATIS-RX is very much influenced by them.
I also assume that the horinontal parts of a wire do the same. So only a= vertical should work.
For operation in city environment smaller antennas at the roof top (old CB= antennas) will possibly work better than the bigger vertical in my garden= between trees and houses at ground level. It might be worth a test.
One of the next tests will be with my gig earth base. I have collected abo= ut 800m of surplus wire. Possibly this is another way to even radiate more= then near field. But I would be very surprised it this was good for any= DX.
I bet Stefans kite antenna will at least be the only way to DX operation.= Unfortunately this is just portable and just temporary.
vy73 Horst DO1KHS/DI2AN
Von: Roger Lapthorn <= rogerlapthorn@gmail.com>
Gesendet: 24.05.2010 18:36:28 Betreff: Re: LF: AW: 8.97kHz - Near field and radiated signals?


Thank you for your fast reply Stefan.

In answer to your questions:
  • Currently, my TX electrode spacing is 10m, which is the best I= can manage in my small garden. Both electrodes are as far away from the= mains and other utility services as I can manage.
  • I have not tried /P transmit testing yet.
  • My n= earest ham who will listen/look is 3kms away, but using beaconing I am= able to go out myself and see how far I can reach. This is what I have do= ne so far, going out into the fields behind my house with electrode pairs= or a loop receiver. Best (by ear reception) DX is 0.35kms, but the system has much scope for optim= isation still.
  • The largest single turn loop I could erect in my garden would be= about 50-70 sq m (about 15m top and 4m-5m high). The longest antenna leng= th would also be 15m horizontal with some vertical section(s) too.
  • The best DX targets are quite modest: I would like to exceed 1km= initially with the TX power I currently have (around 4W). If I could reac= h G6ALB in the next village 3kms away I would be delighted. If I got any= further I would be both amazed and VERY happy!
73s
Roger G3XBM


2010/5/24 Stefan Sch=E4fer <schaefer@hst.tu-darmstadt.de>=
Hello Roger,

For your ground electrodes, ground electrodes may be the best "antenn= a" in some 10...10m. I'm not sure how to calculate field strengths bu= t i just know about the 1/d^3 dependency, so twice the distance means 8 ti= mes the power for the same signal reception, in the near field. But it is the question what are the electrodes since= there is ever a coupling to the mains earth and all the metallic stuff in= regions where people are living so this dependency might not be valid in= your tests. As mentioned here, you could benefit from these conductors...

But if you want to reach more distance with an antenna of the same size (e= .g. of your garden)and the same power, you could try such a TV transformer= . Take a wire, as long as possible and as high as possible, and apply some= kV on it by this transformer. It can even be resonated by adjusting the air gap between the both ferrite parts= . That results in a maximum output voltage and thus "ERP". At le= ast this would be a good alternative to your ground electrode tests. You= could easily compare the reachable distances. Here i would use a E field antenna for reception in the near field.

How far is your next receiving amateur radio station away? And have you tr= ied to do such tests outside the village/city, just like Jim does it with= his loop antenna? This could allow you to increase the distance of your= reception. Here, space is not limited and you could try 2x10m, 2x50m, 2x100m and so on and tell us the differen= ce in the feed point impedance at various frequencies and your ODX :-) May= be i will also do some ground electrode tests in summer but i am still not= sure. The complete receiver of Jim is a really good idea to check the QRM situation at a given QTH. Probably= i will also buit his loop design for such tests... Would be interesing wh= at is the maximum distance for a CW reception of my transmitted signal (wi= th the kite antenna and 6mW ERP) ;-)

I will also do some near field tests in this week, to compare the performa= nce of my 2 grabbers. This will be done here: http://www.google.de/maps?f=3Dq&source=3Ds_q&hl=3Dde&geocode= =3D&q=3Dheiligenberg+heidelberg&sll=3D47.820666,9.312449&s= spn=3D0.106733,0.219383&g=3Dheiligenberg&ie=3DUTF8&hq=3D&h= near=3DHeiligenberg&ll=3D49.419391,8.704101&spn=3D0.001616,0.00342= 8&t=3Dh&z=3D18 in about 1,8km distance to my grabbers. Power will also be below 100W and the antenna wire will be= mounted on a tower in abt 15m height. I will transmit with this TV transf= ormer on a 40m wire.

Roger, what size is your garden? What is the maximum wire length that you= can apply and in which height? What is your goal (best DX, a reals QSO wi= th the next equipped station or just do some funny tests?)

So, wish you fun and success with your experiments!

73, Stefan/DK7FC

PS: What is your locator / QTH?




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

3D""
NEU= : WEB.DE DSL f=FCr 19,99 EUR/mtl. und ohne Mindest-Laufzeit!  =  
http://produkt= e.web.de/go/02/



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



--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k
http://www= .youtube.com/user/g3xbm
G3XBM    GQRP 1678      ISWL G11088
--_000_BF4A524700075746A6467658DFC7102C5106464EE3ICTSSEXC2CAlu_--