On Wed, 26 May 2010, Roger Lapthorn wrote:
- What antenna did you use for RX? Loop, e-field probe?
i used an e-field probe
- Have you tried TXing using grounded electrodes? If so, what range did
you achieve and what RX antenna did you use?
i've tried to couple to various structures (underground wires etc), one of
them worked like a ground dipole. i got around 750m with 1.8W:
http://acid.ch.pw.edu.pl/~sq5bpf/ham/vlf/20100203/vlfcapt3747.jpg this was
in february, during summer the distance would have been smaller.
this is from a bit shorter distance, around 570m:
http://acid.ch.pw.edu.pl/~sq5bpf/ham/vlf/20100203/vlfcapt3744.jpg i have
tried using 40W into a 1.5x2.5m 3 turn loop - in this case there was
marginal copy at the same location (can't find the spectrogram
unfortunately). as you can see in this case it's much better than
marginal.
i've used a loop for both tests. i've tried the location 1.3km away (that
was not a problem for e-field antennas), but didin't receive anything.
actually i would be surprised to receive something at 1.3km, it it was
marginal with half of this distance. so you can see that at least in my
case the e-fields antenna clearly wins
btw performing these tests in the city is not just a matter of turning on
the tx and driving around. you have to search for quiet sites to listen,
and drive there.
jacek
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