Return-Path: Received: from mtain-dj06.r1000.mx.aol.com (mtain-dj06.r1000.mail.aol.com [172.19.187.142]) by air-mc05.mail.aol.com (v129.4) with ESMTP id MAILINMC053-a9694bfad5d130f; Mon, 24 May 2010 15:38:58 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dj06.r1000.mx.aol.com (Internet Inbound) with ESMTP id CE8663800348B; Mon, 24 May 2010 15:38:55 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OGdSR-0006F7-DO for rs_out_1@blacksheep.org; Mon, 24 May 2010 20:37:03 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OGdSK-0006AM-BN for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 20:36:56 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OGdSI-00019z-3S for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 20:36:56 +0100 Received: by bwz16 with SMTP id 16so1190624bwz.16 for ; Mon, 24 May 2010 12:36:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=YE2EwlE8bHWRTzGF6LdpM+x3houz+267mH3mkBtH+mc=; b=A3Vh3muzrWD3Zisc3YSMEqT12RfvS7dzL2mCy4nwz5VI5j/fsddGaKJ3F8kSiaNdGi 92r8FDZe0wSDB9/mRCLaFPQ6p3GG0tz/MKquWNIrH2Hd5tF1AfaVAUJsGmbCFvNwy3iK O5evDhfnnsW/naBY2eIfx4H0uwUmOzcNaFFuk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=X1hb1X/S8whwSXw2+hU2VsqFlNVkjf4B5Xj3oepiR1ZqOBh/j75rJDGG4JZ+AAj96A pgdzDrrc6nIoL4EVIPswmDGIL+iPg6thnbv/wlowOPyYNFs9Qg4TjZmJ59DBPMUw4Y6X 8Eqnvzs+N8xXxgE6n9sXm6Zu8kL+xEOgtNvuQ= MIME-Version: 1.0 Received: by 10.204.155.74 with SMTP id r10mr2162468bkw.128.1274729812570; Mon, 24 May 2010 12:36:52 -0700 (PDT) Received: by 10.204.58.204 with HTTP; Mon, 24 May 2010 12:36:52 -0700 (PDT) In-Reply-To: <315092772.1763254.1274721526409.JavaMail.fmail@mwmweb035> References: <38A51B74B884D74083D7950AD0DD85E82A1C00@File-Server-HST.hst.e-technik.tu-darmstadt.de> <315092772.1763254.1274721526409.JavaMail.fmail@mwmweb035> Date: Mon, 24 May 2010 20:36:52 +0100 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) 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=0015175cda3ea9b54304875c295c X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_MESSAGE, HTML_TAG_EXISTS_TBODY 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m209.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039cdbc9d0b4bfad5cf0b97 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015175cda3ea9b54304875c295c Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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 around 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 was limit= ed 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 wrote: > Hello Roger, Dreamers, > if we define near field as < 2 lambda we are talking about everything be= low > 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 bas= e. > 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 garde= n > 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 > about 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 ca= n > 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 *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. Thi= s is > what I have done so far, going out into the fields behind my house wi= th > electrode pairs or a loop receiver. Best (by ear reception) DX is 0.3= 5kms, > but the system has much scope for optimisation 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= length > 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= reach > G6ALB in the next village 3kms away I would be delighted. If I got an= y > further 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 pow= er >> for the same signal reception, in the near field. But it is the questio= n >> what are the electrodes since there is ever a coupling to the mains ear= th >> 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 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 th= e >> 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 >> tried 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 difference in the feed point impedance at var= ious >> frequencies and your ODX :-) Maybe 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 what is= the >> maximum distance for a CW reception of my transmitted signal (with the= kite >> antenna and 6mW ERP) ;-) >> >> I will also do some near field tests in this week, to compare the >> performance of my 2 grabbers. This will be done here: >> http://www.google.de/maps?f=3Dq&source=3Ds_q&hl=3Dde&geocode=3D&q=3Dhei= ligenberg+heidelberg&sll=3D47.820666,9.312449&sspn=3D0.106733,0.219383&g= =3Dheiligenberg&ie=3DUTF8&hq=3D&hnear=3DHeiligenberg&ll=3D49.419391,8.7041= 01&spn=3D0.001616,0.003428&t=3Dh&z=3D18in about 1,8km distance to my grabb= ers. 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= with >> 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-Laufzeit! > http://produkte.web.de/go/02/ > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0015175cda3ea9b54304875c295c Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Thanks Horst.=A0

I'll try a Marconi antenna at some point, alt= hough 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 electr= ode spacings by connecting one end to the copper pipes in the house, almos= t doubling the effective TX baseline to about 20m. With this, my "ear= th mode" signals were much stronger and I was able to cover fu= rther than before in a "by ear" walk-about test around the field= s.=A0 Ultimate range tonight was 0.4kms using 4W (probably less as the TDA= 2003 was hot and probably turning down the power) and receiving on an 80cm= loop. active HPF, small AF amp and crystal earpiece.=A0 Range was limited= by 50Hz mains hum and background sferic noise. I must try this set-up wit= h my HF up-converter and FT817 this week which has good rejection of 50Hz= =A0 (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.de> 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 ext= remely lucky.
I also do "walkaround tests" near my garden. Bu= t I bet only in the flat field one can see what is possible with small ant= enna 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 antenn= as at the roof top (old CB antennas) will possibly work better than the bi= gger vertical in my garden between trees and houses at ground level. It mi= ght 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 DO1= KHS/DI2AN
Von: Roger Lapthorn <rogerlapthorn@gmail.com>
Gesendet: 24.= 05.2010 18:36:28

An: rsgb_lf_group@blacksheep.org<= br>
Betreff: Re: LF: AW: 8.97kHz - Near field and radiated signal= s?


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 nearest ham who will listen/look is 3kms away, but using bea= coning I am able to go out myself and see how far I can reach. This is wha= t I have done so far, going out into the fields behind my house with elect= rode 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 about= 50-70 sq m (about 15m top and 4m-5m high). The longest antenna length wou= ld also be 15m horizontal with some vertical section(s) too.
  • The best DX targets are quite modest: I would like to exceed 1km initi= ally with the TX power I currently have (around 4W). If I could reach G6AL= B 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-da= rmstadt.de>
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 st= rengths 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 question what are the electrodes since there is ever a coup= ling 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 mentio= ned here, you could benefit from these conductors...

But if you want to reach more distance with an antenna of the same si= ze (e.g. of your garden)and the same power, you could try such a TV transf= ormer. 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 out= put voltage and thus "ERP". At least this would be a good altern= ative to your ground electrode tests. You could easily compare the reachab= le 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 tried 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, 2x= 50m, 2x100m and so on and tell us the difference in the feed point impedan= ce at various frequencies and your ODX :-) Maybe i will also do some groun= d 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 inte= resing what is the maximum distance for a CW reception of my transmitted= signal (with the kite antenna and 6mW ERP) ;-)

I will also do some near field tests in this week, to compare the per= formance of my 2 grabbers. This will be done here: http://www.google.de/maps?f=3Dq&source=3Ds_q&= amp;hl=3Dde&geocode=3D&q=3Dheiligenberg+heidelberg&sll=3D47.82= 0666,9.312449&sspn=3D0.106733,0.219383&g=3Dheiligenberg&ie=3DU= TF8&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 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 QS= O with 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.youtub= e.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
=A0=A0

=
3D""
NEU: WEB.DE DSL f=FCr 19,9= 9 EUR/mtl. und ohne Mindest-Laufzeit!=A0=A0=A0
http://produkte.web.de/go/02/



--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--0015175cda3ea9b54304875c295c--