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LF: VLF_8.79 kHz

To: [email protected]
Subject: LF: VLF_8.79 kHz
From: Stefan_Schäfer <[email protected]>
Date: Mon, 22 Feb 2010 12:32:31 +0100
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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 ;-)

________________________________

Von: [email protected] im Auftrag von Horst Stöcker
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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