it is relative problem-less to rebroadcast withe orthogonal polarization
relative to the original vertical polarized signal and using a loop, not
higher than one meter above ground -- magnetic coupling only...' --
around your house, -- don't forget to change the polarization of the
antenna the ferrite- road which receiving the rebroadcasted signal --
driving with one simple amplifier like LM386, gain not much than 10B.
A few meter outside of the loop will be nothing to receive, no
interference, because 60kHz 's wave length is 5km and it is much larger
that any loop which you could put around you house. The receiving
antenna should be set up that way, that it does not have coupling --
magnetic -- to the transmit antenna, high up in the attic above the
center of the loop.
73
KJ6UHN
Alex
On 12/26/2020 10:45 PM, Charles Steinmetz wrote:
Hal wrote:
Transmitting on the same frequency you are receiving on seems like
asking for
troubles.
Difficult perhaps, but not impossible. As /tvb notes, one solution is
time domain multiplexing; and, as Alex says, phase domain multiplexing
is another (although the phase discrimination of 60kHz antennas this
size is problematic). There are others.
How far apart would the antennas have to be? How would you calculate
that
distance? Or what is the right question?
I've watched discussions of this topic for several years, and have
always been surprised that nobody has ever once mentioned the
potential for harmful interference extending beyond one's own
property. (Tom mentioned it today, including the possibility of legal
implications.) This is especially true of people, like some on this
list, who reportedly run a big loop around their house ("so that all
their WWVB clocks can hear it"). But really, any scheme with leakage
can (and likely does) create harmful interference beyond your property.
I can say positively that if anyone who has such a system lived down
the block from me, I would be most unhappy about it and would be in a
very foul mood by the time I figured out what was causing the
interference I was receiving. (I know whereof I speak -- I spent
quite a lot of effort a few years ago chasing down a leaking 10MHz
reference of very dubious quality in use by a local ham nearly a
kilometer from me.)
So, please, if you are going to rebroadcast a time signal to your
receivers, make sure the modulator and RF generator are in
well-RF-sealed enclosures and that you use good coax (or, preferably,
triax) to send the signal to each receiver individually. BTW, this
applies to *any* such signal, not just LF but HF and GNSS
rebroadcasters as well.
Best regards,
Charles
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