Return-Path: Received: from mtain-dj05.r1000.mx.aol.com (mtain-dj05.r1000.mail.aol.com [172.19.187.141]) by air-df03.mail.aol.com (v129.4) with ESMTP id MAILINDF033-5eec4c0a4bbf6; Sat, 05 Jun 2010 09:06:07 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dj05.r1000.mx.aol.com (Internet Inbound) with ESMTP id EBFA6380000B0; Sat, 5 Jun 2010 09:06:04 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OKt3r-0000BN-AE for rs_out_1@blacksheep.org; Sat, 05 Jun 2010 14:05:15 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OKt3q-0000BD-MQ for rsgb_lf_group@blacksheep.org; Sat, 05 Jun 2010 14:05:14 +0100 Received: from mail-fx0-f43.google.com ([209.85.161.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OKt3n-0004Lk-LC for rsgb_lf_group@blacksheep.org; Sat, 05 Jun 2010 14:05:14 +0100 Received: by fxm11 with SMTP id 11so1443725fxm.16 for ; Sat, 05 Jun 2010 06:05:05 -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=gaJgqIufmeES8CiJ+phmKETTDLQFH5wb3yjJXRNSiqU=; b=gZqJPqw1p+1UwR1NnEGXbF7z7QkLQRc+1qcxkv5TwBhpVXgLjLuyBt1SHxZGRn/s3H tMmG6G+pX8Nk4DJsW4WDcV3Rh5MY4zr5SKQjboJSLWYAUjt6N4uziObFcruU/StMR/iQ Jxpb7R7dyg1c0rw8JguAcdGY81xWvzKyChyJI= 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=tQT4SN3K3rP9yvnLgzU7M2ggeonpfmJWln8LIiheuIsDfAYI97G3+3Vv3x5KuiAMY9 M+jMCLPfxfD0cQFmvhMTOWvv27KBoQ3ZioFBGQR5eyorTi6EvDx7MT6HDMpBQXgkvAJ/ PcRUAAggG3XTl9l3omV7WAn4i3xohAfvCmI08= MIME-Version: 1.0 Received: by 10.204.83.101 with SMTP id e37mr4937457bkl.48.1275743105260; Sat, 05 Jun 2010 06:05:05 -0700 (PDT) Received: by 10.204.58.204 with HTTP; Sat, 5 Jun 2010 06:05:05 -0700 (PDT) In-Reply-To: <4C098CA1.6000008@gmx.com> References: <001401cb02f4$4aa9d130$0401a8c0@xphd97xgq27nyf> <00b701cb030b$c6268d50$0201a8c0@Clemens04> <01CA4D0605FB409ABD7D2F0A98DC46BD@df2py> <4C08002C.5070500@iup.uni-heidelberg.de> <4C09114F.5090605@iup.uni-heidelberg.de> <4C098CA1.6000008@gmx.com> Date: Sat, 5 Jun 2010 14:05:05 +0100 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: VLF: 2km on 8,97 kHz using 6W TX power and a 120m earth antenna Content-Type: multipart/alternative; boundary=0016e6d9a29c9d1bed0488481628 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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: S X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m206.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039cdbc9d0a4c0a4bbc7ab6 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0016e6d9a29c9d1bed0488481628 Content-Type: text/plain; charset=ISO-8859-1 Mike, You asked about my earth electrode set-up, so I'll try to describe it. At the bottom of the back garden I have a copper earth rod about 1.5m long driven into the soil. Here the soil is chalky "clunch". From this earth rod a 2mm diameter PVC covered wire comes up 2m and then runs 10m along the top of the fence before coming up to the bedroom. In the bedroom another short wire 2m long connects to the central heating radiator. A coax cable about 10m long runs back to the TX in the front bedroom effectively bringing the two electrodes to the audio TX connected via a step-up toroidal transformer. Ignoring the loop within the ground, there is about 30 sq m of loop area in the air. I want to try just an air loop (no ground electrodes) to compare signal level at maximum range. Before using the radiator and house pipes as the second electrode I had two 1.5m copper rods 10m nearer the house than the "far" electrode. This one had a baseline of 10m only and was less effective. I'll try to do a drawing and put it on here later. 73s Roger G3XBM , Mike.WE0H wrote: > Hi Roger, > > Could you show me a picture or describe your Earth Electrode antenna? I > have all heavy trees here so no other antenna would likely work. What > feedline? What wire size and what length of the electrodes? Does the wire > run straight away from the feedline in opposite directions to the earth > electrodes or? > > Thanks much, > Mike > WE0H > > > > Roger L wrote: > >> Stefan, >> >> A few observations on your tests using the earth electrode "antenna" >> today: >> >> 1. In my experience, most of the signal transmission is by induction, >> >> so I think it would be worth trying to receive the signal with a >> loop antenna when the received signal may be much stronger than on >> the E-field probe. In my case I use a 30turn, 80cm square, loop >> which can be rotated to minimise 50Hz interference. >> 2. On my 10m and 20m baseline earth electrodes I was measuring >> >> resistance of between 40-60 ohms between 1-9kHz, so your figure >> seems very high. This may be as a result of the soil and rock type >> in your area but this is worth checking. If my theory of the "loop >> in the ground" is correct then a poor conductivity soil would >> result in a larger effective loop area within the ground. >> 3. Did you try matching the PA to this high impedance through a >> >> transformer? I think not in this test, so better results may well >> be possible. >> 4. Regarding Mal's comment about "you need a 100m high antenna", well >> >> you know this works, but the point of this experiment is to see >> how effective, or not, an electrode "antenna" is. The results are >> valuable whether good or not. >> >> Here, I have completed a further "by ear" range test using my TDA2003 4W >> PA into a 20m base electrode pair "antenna" walking around the village in >> many different directions using the 80cm loop RX at around 1.5kHz. I >> improved the 50Hz rejection this week by adding another Sallen-Key HPF. When >> walking over metal pipework in the roads the signal is strong up to at least >> 0.25km in almost any direction and limited by 50Hz noise. When walking >> across fields well away from pipework the loop orientation exactly lines up >> with the base electrode "loop in the ground" at distances up to 0.5km. I >> have not managed to hear the signal at any further distance in any >> direction. My grandson is back staying with us all next week, so very >> limited chance for more experiments until about June 14th. I have a long >> list of things to try still! >> >> 73s >> Roger G3XBM >> > > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0016e6d9a29c9d1bed0488481628 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Mike,

You asked about my earth electrode set-up, so I'll try to= describe it.

At the bottom of the back garden I have a copper ear= th rod about 1.5m long driven into the soil. Here the soil is chalky "= ;clunch". From this earth rod a 2mm diameter PVC covered wire comes= up 2m and then runs 10m along the top of the fence before coming up to th= e bedroom. In the bedroom another short wire 2m long connects to the centr= al heating radiator. A coax cable about 10m long runs back to the TX in th= e front bedroom effectively bringing the two electrodes to the audio TX co= nnected via a step-up toroidal transformer.

Ignoring the loop within the ground, there is about=A0 30 sq m of loop= area in the air. I want to try just an air loop (no ground electrodes) to= compare signal level at maximum range.

Before using the radiator= and house pipes as the second electrode I had two 1.5m copper rods 10m=A0= nearer the house than the "far" electrode. This one had a basel= ine of 10m only and was less effective.

I'll try to do a drawing and put it on here later.

73s
R= oger G3XBM



, Mike.WE0H <we0h@gmx.com>= wrote:
Hi Roger,

Could you show me a picture or describe your Earth Electrode antenna? I ha= ve all heavy trees here so no other antenna would likely work. What feedli= ne? What wire size and what length of the electrodes? Does the wire run st= raight away from the feedline in opposite directions to the earth electrod= es or?

Thanks much,
Mike
WE0H



Roger L wrote:
Stefan,

A few observations on your tests using the earth electrode "antenna&q= uot; today:

=A0 1. In my experience, most of the signal transmission is by induction,=

=A0 =A0 =A0so I think it would be worth trying to receive the signal with= a
=A0 =A0 =A0loop antenna when the received signal may be much stronger tha= n on
=A0 =A0 =A0the E-field probe. In my case I use a 30turn, 80cm square, loo= p
=A0 =A0 =A0which can be rotated to minimise 50Hz interference.
=A0 2. On my 10m and 20m baseline earth electrodes I was measuring

=A0 =A0 =A0resistance of between 40-60 ohms between 1-9kHz, so your figur= e
=A0 =A0 =A0seems very high. This may be as a result of the soil and rock= type
=A0 =A0 =A0in your area but this is worth checking. If my theory of the= "loop
=A0 =A0 =A0in the ground" is correct then a poor conductivity soil= would
=A0 =A0 =A0result in a larger effective loop area within the ground.
<= /div> =A0 3. Did you try matching the PA to this high impedance through a
=A0 =A0 =A0transformer? I think not in this test, so better results may= well
=A0 =A0 =A0be possible.
=A0 4. Regarding Mal's comment about "you need a 100m high anten= na", well

=A0 =A0 =A0you know this works, but the point of this experiment is to se= e
=A0 =A0 =A0how effective, or not, an electrode "antenna" is. Th= e results are
=A0 =A0 =A0valuable whether good or not.

Here, I have completed a further "by ear" range test using my TD= A2003 4W PA into a 20m base electrode pair "antenna" walking aro= und the village in many different directions using the 80cm loop RX at aro= und 1.5kHz. I improved the 50Hz rejection this week by adding another Sall= en-Key HPF. When walking over metal pipework in the roads the signal is st= rong up to at least 0.25km in almost any direction and limited by 50Hz noi= se. When walking across fields well away from pipework the loop orientatio= n exactly lines up with the base electrode "loop in the ground"= at distances up to 0.5km. =A0I have not managed to hear the signal at any= further distance in any direction. My grandson is back staying with us al= l next week, so very limited chance for more experiments until about June= 14th. I have a long list of things to try still!

73s
Roger G3XBM




--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--0016e6d9a29c9d1bed0488481628--