Return-Path: Received: from mtain-de07.r1000.mx.aol.com (mtain-de07.r1000.mx.aol.com [172.29.64.207]) by air-md02.mail.aol.com (v129.4) with ESMTP id MAILINMD022-8b794c25ac332e8; Sat, 26 Jun 2010 03:28:51 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-de07.r1000.mx.aol.com (Internet Inbound) with ESMTP id F20BB380000AC; Sat, 26 Jun 2010 03:28:43 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OSPnA-0007OE-Ie for rs_out_1@blacksheep.org; Sat, 26 Jun 2010 08:27:08 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OSPn9-0007O1-HY for rsgb_lf_group@blacksheep.org; Sat, 26 Jun 2010 08:27:07 +0100 Received: from mail-wy0-f171.google.com ([74.125.82.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OSPn8-0001Ea-6O for rsgb_lf_group@blacksheep.org; Sat, 26 Jun 2010 08:27:07 +0100 Received: by wyf28 with SMTP id 28so1986447wyf.16 for ; Sat, 26 Jun 2010 00:27:00 -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=Aunp7zK0r/zsyN/KyQdvjlYSt9+TebU61k8APhejNpY=; b=GGoWlaeLm/x48gLGswWWgEW8BAiLhJFF3OiQRqrTk6W3zxQTSZDWuOMvrUBo5lniEM zo7XDqxvFY93ahr8EAD1JYvBLGqy/J55jYeY6qxxWlNtjTdLE1PNypkiQn09xAu9uQJY y6o7G/1U0HN53ztXbiNFywZmdX9Rvbs9CCoak= 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=sSYuqoO+G8ge3/1OxBosvZvi9O1xF9i/MDhDAYEsN//8wecF+JGcZm1mCph06/VgDB lL0AU/TYzl8izOHJ89AFemsWVDyqGFcmH1wu/S8Sd8EWXS10jIAPadNY3TcMmu9aaVMe IbhS9ufmnpC8jYgWeSsTg+NhoghaXCdAlzEEE= MIME-Version: 1.0 Received: by 10.216.86.16 with SMTP id v16mr1365890wee.111.1277537220144; Sat, 26 Jun 2010 00:27:00 -0700 (PDT) Received: by 10.216.52.7 with HTTP; Sat, 26 Jun 2010 00:27:00 -0700 (PDT) In-Reply-To: <38A51B74B884D74083D7950AD0DD85E82A1C66@File-Server-HST.hst.e-technik.tu-darmstadt.de> References: <4C23FC42.8040204@iup.uni-heidelberg.de> <38A51B74B884D74083D7950AD0DD85E82A1C66@File-Server-HST.hst.e-technik.tu-darmstadt.de> Date: Sat, 26 Jun 2010 08:27:00 +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: 5,2 km distance on 8,97 kHz with an earth antenna Content-Type: multipart/alternative; boundary=0016e6d588b931ae1b0489e9d0af 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: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m278.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40cf4c25ac2b28cd X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0016e6d588b931ae1b0489e9d0af Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Good luck with the next tests Stefan. Yes I agree that a poor conductivity soil/rock should give the largest "lo= op in the ground" (and best range) and that low contact resistance at each earth point will allow you to maximise the current into the ground loop. *I wonder if any electromagnetic theorists here would be able to estimate the radiated power of such an earth mode "antenna"? * Such structures (on a larger scale) were used at 76Hz for the USA's Projec= t Sanguine to communicate with their nuclear submarines at great depths. At 8.97kHz the electrode spacing could be 176 times shorter. Also, we are not trying to counter many dBs attenuation in seawater, nor span the entire globe. Also, with slow QRSS we can wait for our signal to appear and use extremely narrow bandwidths. So, what I'm wondering is what do the maths say might be possible regardin= g *radiated *signals from such structures? 73s Roger G3XBM 2010/6/26 Stefan Sch=E4fer > Tnx Roger, > > Today i have prepared further 9 rods for each pole, so 20 rods for each > pole in sum now. Tomorrow in the morning i will drive again on the hill= and > try to even reduce the losses. When DHO38 comes back after its break arr= ound > 7...8 UTC i will try to transmit a message to my grabber using about 50 > watts. I have already an idea what to transmit ;-) > > I have thought about the losses problem: First we say that it is importa= nt > to have a low ground conductance so that we achieve a big loop in the > ground. But next we say that we need a very low local earth resistance= at > the poles. There on the mountain the earth conductivity seems to be very= low > and THUS it is not easy for me to get a low losses at the poles. It is= the > same dependency! Thus i have to do more effort to come down with the los= ses > but it is better than taking just one 20cm rod and achieve 100 Ohm since= it > would mean that the loop area is small as well! Preparing those small ea= rth > rods is no problem. Even if i would need 100 for each pole i would do it > (not worth to mention, compared to the work to wind such a coil ;-) ). > > Today in the morning the QRN was pretty low but in the afternoon it rain= ed. > I hope for good conds tmw. :-) > > In further tests i plan to study the influence of rain and temperature= and > so. This can be done by using QRP (e.g. 1W TX power, supported by a sola= r > cell and a battery) and my DFCW-6000 window or even the DFCW-60000 windo= w > that will cover about 7 weeks! > The 60000' window is running since about 2 weeks and is available here: > http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.htmlDFC= W-60000 is not really suited for a QSO of course but it gives a good > overview of the QRN dependency during the summer time. And it is suitabl= e > for transmitter tests if one can run a transmitter for some days or a we= ek. > Even slower, i have added a "Annual overview" window but it will take so= me > months to have a real information there... > > 73 es gl, > Stefan/DK7FC > > > ________________________________ > > Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Roger Lapthorn > Gesendet: Fr 25.06.2010 09:44 > An: rsgb_lf_group@blacksheep.org > Betreff: Re: VLF: 5,2 km distance on 8,97 kHz with an earth antenna > > > This is excellent Stefan. > > In your case it is much more probable you are seeing true earth mode > propagation not aided by utilities in the ground, although it is hard to > avoid them. It will certainly be worth trying reception on a loop antenn= a > with the loop orientated both (a) in alignment with the earth electrode= loop > and (b) flat on the ground. Also it is worth trying a lower frequency li= ke > 838Hz where I've been doing my recent tests. > > In all, I am VERY excited about your tests and results. Thanks for shari= ng > them here. > > Last night I managed to get 5.25km (my best DX yet), but this was > definitely aided by utilities. Tests at many other locations out as far= as > 6km to the west and north totally failed to produce even a faint trace= on > the Spectran screen using QRSS3 on 838Hz. Information on my website as > usual. See http://sites.google.com/site/g3xbmqrp/Home/earthmode . > > 73s and good luck > > Roger G3XBM > > > > 2010/6/25 Stefan Sch=E4fer > > > Dear LF/VLF, > > Today i spent more than 8 hours in the forest on a hill 520m ASL, > improving and experimenting with my VLF earth antenna. It was a fantasti= c > and very successful day that gave a lot of fun and motivation. BTW, just > spending time in this wonderful nature with all its beauty cannot be was= ted > time even if all the experiments would fail :-)))) That is what i though= t > many times this day. If you live in a city with much noise (on the band= and > audible) you may understand what i mean when i say that all you can hear > there is the wind and some birds! > > Since there are a lot of photos and things to tell i set up a pdf > document with my report that is available at > http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF_5km_with_an_earth_ante= nna.pdf, for the VLF enthusiasts (Dreamers!) and those who want to become= one! :-) > > Best 73, Stefan/DK7FC > > > > > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > G3XBM GQRP 1678 ISWL G11088 > > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0016e6d588b931ae1b0489e9d0af Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Good luck with the next tests Stefan.

Yes I agree that a poor cond= uctivity soil/rock should give the largest "loop in the ground"= (and best range) and that low contact resistance at each earth point will= allow you to maximise the current into the ground loop.

I wonder if any electromagnetic theorists here would be able to est= imate the radiated power of such an earth mode "antenna"?=

Such structures (on a larger scale) were used at 76Hz for the= USA's Project Sanguine to communicate with their nuclear submarines= at great depths. At 8.97kHz the electrode spacing could be 176 times shor= ter. Also, we are not trying to counter many dBs attenuation in seawater,= nor span the entire globe.=A0 Also, with slow QRSS we can wait for our si= gnal to appear and use extremely narrow bandwidths.

So, what I'm wondering is what do the maths say might be possible= regarding radiated signals from such structures?

73s
Rog= er G3XBM


2010/6/26 Stefan Sch=E4fer= <sch= aefer@hst.tu-darmstadt.de>
Tnx Roger,

Today i have prepared further 9 rods for each pole, so 20 rods for each po= le in sum now. Tomorrow in the morning i will drive again on the hill and= try to even reduce the losses. When DHO38 comes back after its break arro= und 7...8 UTC i will try to transmit a message to my grabber using about= 50 watts. I have already an idea what to transmit ;-)

I have thought about the losses problem: First we say that it is important= to have a low ground conductance so that we achieve a big loop in the gro= und. But next we say that we need a very low local earth resistance at the= poles. There on the mountain the earth conductivity seems to be very low= and THUS it is not easy for me to get a low losses at the poles. It is th= e same dependency! Thus i have to do more effort to come down with the los= ses but it is better than taking just one 20cm rod and achieve 100 Ohm sin= ce it would mean that the loop area is small as well! Preparing those smal= l earth rods is no problem. Even if i would need 100 for each pole i would= do it (not worth to mention, compared to the work to wind such a coil ;-)= ).

Today in the morning the QRN was pretty low but in the afternoon it rained= . I hope for good conds tmw. :-)

In further tests i plan to study the influence of rain and temperature and= so. This can be done by using QRP (e.g. 1W TX power, supported by a solar= cell and a battery) and my DFCW-6000 window or even the DFCW-60000 window= that will cover about 7 weeks!
The 60000' window is running since about 2 weeks and is available here= : http://www.iup.uni-heidelberg.de/schaefer_vlf/= DK7FC_VLF_Grabber2.html DFCW-60000 is not really suited for a QSO of= course but it gives a good overview of the QRN dependency during the summ= er time. And it is suitable for transmitter tests if one can run a transmi= tter for some days or a week. Even slower, i have added a "Annual ove= rview" window but it will take some months to have a real information= there...

73 es gl,
Stefan/DK7FC


________________________________

Von: owner-rsgb_lf_g= roup@blacksheep.org im Auftrag von Roger Lapthorn
Gesendet: Fr 25.06.2010 09:44
An: rsgb_lf_group@blackshe= ep.org
Betreff: Re: VLF: 5,2 km distance on 8,97 kHz with an earth antenna


This is excellent Stefan.

In your case it is much more probable you are seeing true earth mode propa= gation not aided by utilities in the ground, although it is hard to avoid= them. It will certainly be worth trying reception on a loop antenna with= the loop orientated both (a) in alignment with the earth electrode loop= and (b) flat on the ground. Also it is worth trying a lower frequency lik= e 838Hz where I've been doing my recent tests.

In all, I am VERY excited about your tests and results. Thanks for sharing= them here.

Last night I managed to get 5.25km (my best DX yet), but this was definite= ly aided by utilities. Tests at many other locations out as far as 6km to= the west and north totally failed to produce even a faint trace on the Sp= ectran screen using QRSS3 on 838Hz. =A0Information on my website as usual.= See http://sites.google.com/site/g3xbmqrp/Home/earthmode .
73s and good luck

Roger G3XBM



2010/6/25 Stefan Sch=E4fer <Stefan.Schaefer@iup.uni-heidelberg.de>


=A0 =A0 =A0 =A0Dear LF/VLF,

=A0 =A0 =A0 =A0Today i spent more than 8 hours in the forest on a hill 52= 0m ASL, improving and experimenting with my VLF earth antenna. It was a fa= ntastic and very successful day that gave a lot of fun and motivation. BTW= , just spending time in this wonderful nature with all its beauty cannot= be wasted time even if all the experiments would fail :-)))) That is what= i thought many times this day. If you live in a city with much noise (on= the band and audible) you may understand what i mean when i say that all= you can hear there is the wind and some birds!

=A0 =A0 =A0 =A0Since there are a lot of photos and things to tell i set= up a pdf document with my report that is available at http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF_5km_w= ith_an_earth_antenna.pdf , for the VLF enthusiasts (Dreamers!) and tho= se who want to become one! :-)

=A0 =A0 =A0 =A0Best =A073, Stefan/DK7FC





--
http://g3xbm-= qrp.blogspot.com/
http://ww= w.g3xbm.co.uk <http://www.g3xbm.co.uk/>
http://www.youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088




--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--0016e6d588b931ae1b0489e9d0af--