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Message-ID: <01C3A2B647BB4AF099A4BC1947CF2E45@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <AANLkTiktwkR3TIh1fAxUX0ZpOA4cbRyA3KEisabHoqrP@mail.gmail.com>	<4C363DCD.303@iup.uni-heidelberg.de>	<4C3650A1.6040104@iup.uni-heidelberg.de>	<BF4A524700075746A6467658DFC7102C51094D0E37@ICTS-S-EXC2-CA.luna.kuleuven.be>	<4C3DA75D.80407@iup.uni-heidelberg.de>	<BF4A524700075746A6467658DFC7102C51094D0E44@ICTS-S-EXC2-CA.luna.kuleuven.be>	<263121BD51374246B3F184A43B2E9619@JimPC>	<BF4A524700075746A6467658DFC7102C51094D0E45@ICTS-S-EXC2-CA.luna.kuleuven.be>	<4C3E27D4.3060407@iup.uni-heidelberg.de>	<E21763BAE3DF42FAA9E57979CFC3F5CD@JimPC>	<3F71CB69-5F2E-4BEE-BB5E-651DA77CC39E@numeo.fr> <AANLkTimdMhlOIzUEkP4puuP0ea6jZQ1stjQ58SwcMO_w@mail.gmail.com> <4C3F76CB.1020709@iup.uni-heidelberg.de> <4C40DAEB.3010500@iup.uni-heidelberg.de> <4C40DDE8.4070507@iup.uni-heidelberg.de>
In-Reply-To: <4C40DDE8.4070507@iup.uni-heidelberg.de>
Date: Sat, 17 Jul 2010 22:43:10 +0100
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Subject: LF: RE: DLF passive received with earth antenna
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Dear Stefan, LF Group,

It gets confusing when the bandwidth changes! In this case, both measu=
rement=20
bandwidths are much smaller than the modulation bandwidth, and the sig=
nal=20
has a continuous spectrum,  so it is reasonable to assume the measured=
=20
signal power will be proportional to the measurement bandwidth. The=20
amplitude of the signal on the earth antenna was -20dB in 3Hz BW. To=
=20
normalise the measurements to a 3Hz FFT BW, you need to add 6dB to the=
=20
amplitude of the 1m^2 loop signal in 0.75Hz bandwidth, to give -94dB=
 as you=20
said.  The ratio of signal amplitudes is then 74dB, or a factor of abo=
ut=20
5000. So the eqiuvalent area of the earth antenna is 5000m^2.

Adding Markus' factor of 11dB to give the total signal amplitude from=
 the=20
1m^2 loop gives -83dB, 74 dB below your reference level of 44mV =3D -9=
dB.=20
Therefore the 1m^2 loop EMF is about 9uV, corresponding to FS of DHO38=
 being=20
about 18mV/m. If this is correct, it corresponds to about 1.1MW ERP,=
 which=20
is impressive, but since the signal is down in the noise in your syste=
m,=20
these figures can only be a very rough estimate.

Cheers, Jim Moritz
73 de M0BMU

----- Original Message -----=20
From: "Stefan Sch=E4fer" <schaefer@iup.uni-heidelberg.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Friday, July 16, 2010 11:32 PM
Subject: Re: LF: RE: DLF passive received with earth antenna


> Ehm, 18000m^2? I have just calculated 5000m^2. It is A =3D 1m^2 *=20
> 10EXP((-94--20)/20), right?
>
> 73, Stefan
>
>=20