Ok Roger,
And do you know if f<9kHz is free for other countries in europe as
well? What about the UK?
If such a grounded dipole is best, than it is easy to build a big
antenna without the problems we have on LF (getting the wire high above
ground). So we also could try big/long antennas. Waht do you mean with
amateur levels? Power range is clear, something arround 500W+-6dB. But
the antenna? Sure, if you think about building an antenna in the
garden, say 2x20m, is not very effective but what about 2x500m in a
forrest, perhaps with the loading coils (which will be on a ferrite
toroid i think) mounted 300m apart from the center? That could be
interesting and easy to try. No tower, no earth radials, just 2 wires
hung up on some trees and measured the impedance at the feed point,
that would be a first step.
This antenna will still be bad but what we are doing -on LF it is the
same- is beeing fascinated to reach a good distance and make some
contacts at very low frequencies, although it would be much easier on
40/80m...
And so, if one would reach 50km with such a short dipole, the
fascination would be enormous, isn't it? ;-)
Has anyone, except Horst, tried such experiments as well?
With the ground wave, one could reach the whole europe, i expect. But
that are dreams...
Stefan/DK7FC
Am 22.02.2010 11:03, schrieb Roger Lapthorn:
At this frequency, widely spaced, grounded electrode pairs are
probably the best "antenna". There are references to how these work in
the literature (for example NATO AGAARD papers from the 1960s,
available on the internet I believe) and on one of the German ham sites
(DK8KW) - see http://www.qru.de/#vlf .
Don't expect great ranges: up to 10kms is a fair aim with modern
signal processing technology and reasonable (amateur levels) available
power. Project Sanguine achieved worldwide coverage to submarines at
76Hz (yes Hertz!) but used enormous power and antennas stretching for
100s of kms.
73s
Roger G3XBM
2010/2/22 Stefan Schäfer <[email protected]>
Hello Horst,
That sounds really nice. If it would be easy to find some motivated OMs
in the near field (31km) ;-), that would be an interesting field to
test.
Yesterday i have thought about possible antenna configurations for that
range and got the idea that one could use a forrest as an antenna
tower. There, you could hang up 100s meters of wire, in series and in
parallel. You do not need to have that area beside your house. Nobody
will see the wire and nobody will care about it.
Since summer 2007 i have a horizontal loop antenna mounted in some
trees on my hill with excellent results on all HF bands and also 160m.
The loop has 130m and is mounted up to 12m above ground. Perfect
matching from 160m to 10m with my symmetric tuner. I even tried
matching on 2200m without a problem but with bad ODX results, of
course. But if one would try 2x 10*100m on VLF, the ODX would be
interesting...
JO30OT is abt 160km from JN49IS and thus a little far i think ;-)
What is your RX antenna and have you already catched some commercial
VLF stations in that range? Are there some?
73, Stefan
PS: One can be sure that there will never be SSB operation ;-)
Gesendet: Mo 22.02.2010 09:29
Betreff: RE: LF: AW: Beaconing on 8.79 kHz in QRSS
Hallo Stefan,
there was a notice in Funkamateur 12/05, S. 1287, that in DL the range
<9kHz is free.
I could not believe that so I asked the BNetzA and after a while I got
a letter which confirmed that.
So there nothing you've got to do for getting a licence. You do not
need one.
There is no limitation of technical parameters like bandwith or power.
Hard to believe in german, but obviously true.
My QTH is Siegburg JO30OT
Horst
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Dipl.-Ing. Stefan Schäfer
Institut für Umweltphysik der Universität Heidelberg
Im Neuenheimer Feld 229
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[email protected]
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Fax: (+49) (0)6221 546405
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