We did a loop tx experiment with Marcin SQ2BXI on 20 january 2018.
The tx was a semi-horizontal 1-turn loop about 150x50m (from memory), 1A
current at 8270Hz. The tx frequency was generated via Paul's ebsynth, and
locked to GPS.
The signal was detectable 2km away in the H-field, don't remember the
exact parameters, but we were using Spectrum Lab and no decimation, so
either 366mHz, 183mHz, or 91mHz bins (i think Marcin has this data,
including waterfall plots etc).
The signal was not detectable in the E-field almost 1/4 wavelength away
(abt 7-8km) in my RX site (GPS locked) when i analysed a 1 hour recording.
Theoretically after 1/4 wavelength we should see an E-field component if
there was any far-field radiation. This is the reason we haven't published
anything about it so far (but we will when we get some free time).
I've also tried tx experiments years ago with vertical loops: 3 turns
1.5x2.5m on my balcony (detectable at about 500m from the loop), and
1-turn about 2x20m (detectable at about 800m). This was a long time ago,
so now i would probably add 20% distance just by using better dsp
settings, but still nothing that spectacular. When you're 100m from the
coil the signal is very strong, but diminishes with distance quicky. If
you want some semi-DX in the H-field, then try coupling into some long
conductors (pipes, power lines, railway tracks etc).
VY 73
Jacek / SQ5BPF
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