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
