Hi Jim,
I hope you don't mind that i'd like to share the email with the
reflector, because i've a thought that might be interesting.
In my view, the Loomis experiment it is rather the detection of a
changing current (charge per time) on the RX site. The changing current
is coming from a change in the static electric field, caused by the
shortcutted 'TX' antenna. Something like a current divider.
In 2010/2011 i've done VLF transmissions on my own, using a 300m
vertical kite antenna (having a special licence for that altitude). The
antenna capacity was about 1.5 nF. During an experiment in the summer
time there was a short moment when the vertical wire was floating. It
quickly charged up to some kV, which was quite noticable when i catched
and touched the wire then!! Since that time i carefully kept the wire
grounded during such experiments.
So, it means that the wire charged up, so there must be some continuous
charge flowing onto the wire and, if the wire would be grounded
permanently, you could probably measure a more or less stable current,
i guess it would be some 100 uA.
Now imagine someone else would rise a grounded kite in a few meters
distance. This would certainly affect the current flowing in my kite
wire. The farer both 'antennas', the lower expressed the effect will be
and the higher the antennas, the stronger it will be expressed.
I think the effect would be much better expressed by measuring the
voltage across a 1 MOhm resistor instead, which could be done by using
a scope and some overvoltage protection!
Actually an interesting question: In the summer time, which DC voltage
could be measured over a 1 MOhm resistor when connecting to a large E
field antenna and ground?
And, a next step: If i let my antenna charge up (floating) and then
discharge it in exact time intervals, say each second, then i should
see something at 1 Hz on a suitable receiver. This would already come
close to the experiment i'v done. I'm just replacing the 'natural
charge source' by a high voltage power supply and modulate that voltage
(with a sine wave, not rectangular).
So, to answer your question, i think that Loomis experiment was not
dedicated ELF, it was rather a broad-band spectrum that was radiated,
since the charged antenna was discharged immediately. For a real ELF
transmission i would say that the carrier frequency has to be at ELF,
not the modulating frequency. OK here you might say the carrier
frequency is 0 and it is AM modulated...
Try to repeat the experiment! Use smaller antennas and shorter
distances. Could be interesting :-) Rise two 10m high wires in 10m
distance in an open field. Connect one of them to a scope (1 MOhm input
resistance), protect the input with a glow lamp. Keep the other wire
floating. Select 1 second/div. If there is a thunderstorm coming and
you can see a rising DC level on the scope, then do a shortcircuit on
the other wire. I bet you will see the voltage dropping on the scope.
73, Stefan
Am 09.03.2019 19:10, schrieb James Hollander:
Hi Jacek
and Stefan, I’d like to suggest that
while I can’t say for sure there weren't ELF frequencies received in
the Loomis
experiment of 1866, I’m hesitant to reach the conclusion ELF was used
by Loomis because of the
following questions.
1) If the transient current that flowed when
Loomis’ transmitter circuit was closed probably lasted only a few
milliseconds,
wouldn’t the modulation frequency content exceed
at least the upper ELF boundary 30Hz as impressed on the “carrier”?
2) With a 600’ long TX
antenna and only a
galvanometer fed by similar height RX antenna, wouldn’t any radio waves
that might
have been received be shorter than 10x the wavelength for which a 600’
TX
antenna is a quarter wavelength? 10x(600’x4)=24000’
or about 8km. If the wavelength is less than
about 8km, wouldn’t
the “carrier” frequency content exceed about
37 KHz?
3)
Nevertheless, one might say, if galvanometer deflected
temporarily in Loomis’
system, it must have detected some near-DC content unless some
nonlinear
element were in the receiving circuit. If
I Fourier Transform a damped DC transient, what is the frequency
content?
4)
If there were DC transfer, wouldn't we say it's in the nature of a
current charging an
atmosphere-ground capacitance through the ground resistance, not radio
in near
field ELF? Or
should we say the meaning of “frequency” in this case becomes so fuzzy
that
Loomis both did and didn’t use ELF?
5) If
indeed Loomis communicated any ELF, can’t
one still radically distinguish the 12.67 Hz experiment at DK7FC as
involving a
very narrow band continuous
wave with 227 hours integration of
this continuous wave to detect it and make it separable from other
waves that
could be generated in the ELF band?
I’m
new to the subject of ELF, and would appreciate any words of wisdom
you’d like
to give.
Vy 73,
Jim Hollander W5EST
-----Original
Message-----
From: Jacek Lipkowski <[email protected]>
To: rsgb_lf_group <[email protected]>
Sent: Sat, Mar 9, 2019 4:28 am
Subject: Re: LF: RE: RE: Almost touching the ground... | 12.47 Hz
Actually a similar experiment to Stefan's has been
done already, and at
much lower frequencies (almost 0Hz :):
http://aerohistory.org/Wireless/loomis.html
In this case the power supply is from the cloud electric field and
probably had quite a few more kV than Stefan's.
Please note the DX distance.
VY 73
Jacek / SQ5BPF
Hi
ELF friends, During the last 2 weeks i've
done
another experiment on ELF, this time
on 12.47 Hz, the 24 Mm band (wavelength 24057 km). Again i've crossed
the local
distance of 3.5 km. That's the lowest frequency i've ever been and it
feels
like i can see the ground already :-) The
dimensions of everything down there are extreme. I've integrated 227
hours of a
carrier transmission into one spectrum peak, it is shown in the
attachment in
1.25 uHz. This carrier could have transferred an EbNaut message of
nearly 100
characters.
The ERP was 50 attowatt or -163 dBW and the antenna current was 170 uA
only,
despite about 5 kV antenna voltage.
I'm now trying to put a step below 10 Hz but the RX antenna becomes
less
efficient with each Hz. 73, Stefan
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