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Re: LF: RE: Summer games / EARTH ANTENNAS

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Subject: Re: LF: RE: Summer games / EARTH ANTENNAS
From: Eike DL3IKE <[email protected]>
Date: Wed, 4 Jul 2018 18:03:09 +0200
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Hi all,

what about these antenna ideas:
Find a cross between a guardrail on a freeway and a non-electrified railroad.
Connect one pole of the transmitter to the guardrail and one pole to the railroad.
Also possible: connect one pole of the transmitter to the grounding of the power connection
and one pole to the telephone line, which hangs a long distance on wooden poles.

In both cases, the signal is spread over many kilometers.

30m aluminum foil strengthened with 30m bookbinding foil results in an area of approx. 18m ² to free space around.
The slide can be pulled up by a kite as a top load and result in higher antenna currend.
The kite antenna can also use the guardrail, the railwaytrack
or the ground of the energy supplier as ground.

These are certainly unusual ideas. But I think they´ll work well

70 Bäume de Eike DL3IKE


BTW did someone (of the group) ever tried to build a full size dipole for 137 kHz? I mean for transmitting! On a stony mountain/hill it could be better than expected. With a Raspi + GPS module one could build up a simple WSPR beacon and a ICL7667, which can be driven by the 3.3 V GPIO output voltage could make a simple and effective 5W PA running at 12V.
The wire just needs to be 1000m long or so. In a low frequented forest it could lay there for some days...

I remeber experimenting with a full size dipole on 630m in 2012, when the band was quite young. It worked well although the antenna was just 4m above the ground and the soil conductivity was not ideal (medium conductivity). A few CW QSOs were done out of a 7 Ah gel battery and just 50W or so, in July!

And what about VLF and ULF using earth antennas? I remember making 45 km distance on 8.97 kHz from the 700m long wire antenna, grounded at each end (250W RF power if i remember correctly). That was about 15 dB in 3.8 mHz. But what would be possible on lower frequencies if the far end of the wire is well grounded?

Time to fill that summer hole (activity)!

73, Stefan


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