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On Sunday, March 10, 2019 10:52:09 AM you wrote:
> Hi Jacek, DC,
>
> Yes yes, i already see a new project for summer :-)
>
> A floating antenna will charge up to a voltage where the E field
> strength is high enough to start partial discharges, something like 20
> kV maybe, depending on the wire diameters and homogenity of the
> arrangement, also on pressure and humidity. So there will be a voltage
> limit given by the arrangement. But a higher field strength in summer
> will help to charge up the antenna faster, so higher switching
> frequencies are possible.
Here some interesting paper about Atmospheric Electric-Field Gradients
https://pdfs.semanticscholar.org/f67f/4a4908835530a87613d9922d07e6748ff9ea.pdf
Claudio IK2PII
>
> One could build/use a triggered spark gap,
> https://en.wikipedia.org/wiki/Trigatron, this will hold higher voltages
> and you can connect the trigger directly to a ublox GPS module running
> e.g. at 3 Hz :-) I think this will give a lower jitter than when using a
> vacuum relay.
> Could this work over my 3.5 km path if i use my inv-L? I don't think so.
> The time to integrate will be to short and there will be much QRN during
> such an experiment, so the SNR will be very low. Currently (at 12.47 Hz)
> i already have 15 kV DC available...
>
> Anyway, interesting questions, there is something interesting to learn.
> Maybe i will do a few experiments in summer. Building a HV divider and
> measurement should be no problem...
>
> 73, Stefan
>
> PS: Assuming 100 uA constant current 'coming from the sky', my 470 pF
> antenna would charge up with 213 kV/s, so it would be possible to switch
> at 10 Hz and get a 21 kV 'square wave'. Maybe the harmonics could be
> detected easier than the fundamental frequency.
> At 137 kHz it would be 1.5 V only (0.53 V rms). This can be switched
> with a normal FET! Imagine we would switch the antenna permanently at,
> say 136.172 kHz, using a FET and a ublox GPS module. Then, as soon as
> the field strength is high enough, we would see a carrier on the
> grabbers? We need to try that out! Amazing! What a great hobby we have!?!
> PPS: For this experiment, the antenna can be series resonated, which
> would help to concentrate the energy to the wanted spectrum...
>
> Am 10.03.2019 09:58, schrieb Jacek Lipkowski:
> > I haven't tried this with 300m kites, but even ordinary low-band
> > dipoles can charge quite quickly if they are high enough, so 100uA
> > seems to be a good approximation. This is already comparable with the
> > 170uA you're getting at 12.71Hz now (and which will be lower at lower
> > frequencies).
> >
> > The only problem is the switch, but a high voltage vacuum relay (or a
> > few in series with a piece of fiberoptic for controlling each of them)
> > should be sufficient upto a few Hz.
> >
> > Also note that the more charge in the atmosphere, the more ERP you
> > get. But it also gets more dangerous. No risk no fun on the "loomis
> > band" :)
> >
> > VY 73
> >
> > Jacek / SQ5BPF
> >
> > On Sat, 9 Mar 2019, DK7FC wrote:
> >> Date: Sat, 09 Mar 2019 22:31:41 +0100
> >> From: DK7FC <[email protected]>
> >> Reply-To: [email protected]
> >> To: "[email protected]" <[email protected]>
> >> Subject: LF: Re: Re Loomis? & ... 12.47 Hz
> >>
> >> 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
> >>
> >> From: DK7FC <[email protected]> To: rsgb_lf_group
> >> <[email protected]>
> >> Sent: Tue, Mar 5, 2019 12:50 pm Subject: ELF: Almost touching the
> >> ground... | 12.47 Hz
> >> 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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