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:content-transfer-encoding;
        b=d9VKdz98RgpSaGx5ApJPgWNy1ciiwAEJWqsClXXAQoSMrCsu48eM33TJQvfnvd56qL
         bG24ViH2RJLbuF1+9moDTh5YwW4uslJP3/E35zHjQK+PUCMDNTcY2BNrILH/n1ndh27q
         zBRcCBF/dLePdQkqtdT9OCyKUAok3F5xlSeko=
MIME-Version: 1.0
In-Reply-To: <EF9DB1FF-7808-4E78-8A91-99C5961CF353@numeo.fr>
References: <AANLkTik25SxY1Uo0BLO5wCPPak_xr4ZnQzp4CbDqkAON@mail.gmail.com>
	<Pine.LNX.4.64.1102032010470.1022@paranoid.lipkowski.org>
	<EF9DB1FF-7808-4E78-8A91-99C5961CF353@numeo.fr>
Date: Fri, 4 Feb 2011 10:22:53 -0500
Message-ID: <AANLkTimhz7qdxYApxFDjs4VSbKhkbv7+FL=kj-HJESO4@mail.gmail.com>
From: Warren Ziegler <wd2xgj@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: Earth-mode or not earth-mode
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


John,
    If this was conduction through the rail, why was it limited to 1.6kM?
Was this the length of unbroken track?

--=20
73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1




On Thu, Feb 3, 2011 at 3:08 PM, John Rabson <john.rabson@numeo.fr> wrote:
> Some years ago, we tried using a small loop to couple a Heyphone (4 W ou=
tput on 87 kHz) into a running rail in a disused railway tunnel in the Eng=
lish Midlands (we had permission from the owners of the line). =A0A simila=
r setup was used for receive and we achieved a range of 1.6 km along the=
 line.
>
> 73
> John F5VLF
>
> On 3 Feb 2011, at 20:36CET, Jacek Lipkowski wrote:
>
>> trying to couple to large structures is an interesting experiment, both=
 for receiving and transmitting (only by induction of course :). think abo=
ut power lines, phone lines (but unfortunately nowadays most are very shor=
t, and the rest is done via fiber), natural gas pipelines, railways etc.=
 this is an example rx experiment: http://www.youtube.com/watch?v=3DsWsdaS=
mWg7E , these structures are usually very well grounded at regular interva=
ls, but still some vlf will slip through the ground system, so they can be=
 also used for tx too. a few miliamps at 9kHz into a large structure is de=
tectable from a few hundred meters.
>>
>> actually the "utilities-assisted earth mode" works not only on transmit=
. a loop antenna near a long conductor will pick up a stronger signal (and=
 also more qrm, so this doesn't always raise S/N).
>>
>> this might not be ham radio (or not radio at all), but is very interest=
ing nevertheless
>>
>> VY 73
>>
>> Jacek / SQ5BPF
>>