A Comment on Antennas for Transatlantic QSO
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2 kilometers is a good wavelength. Then you have the
chance somewhere to find some Hams living about a
quarter of the wavelength apart from each other.
If they all synchronize their LF-transmissions and
adjust the phases such that all the power goes west
nothing will be lost in other directions and all will
be summed up over the atlantic. That's the simple
principle of phased arrays often used by military
RADAR. You will observe the same antenna gain when
receiving. Depending on the location you can get
11 dB antenna gain with 8 stations, but, in contrast
to a Yagi, the power is 8-fold, so the over-all-gain
may be 20 db at the transmitting end. This effort
of course is only justified, when all the individual
antennas are nearly equal and very good.
May be, it's out of law, to transmit in phase from
so many places using the same call sign.
My little LF-tranceiver entirely is synchronized to
DCF-77 and can be shifted in phase by the PC. Some
of this type used in a phased array would not need any
communication between each other while transmission.
Only the phases must be calculated once using the
exact coordinates of each antenna location, and the
time interval of the transmission and the information
to be transmitted should be the same, of course.
Reception would need to bring the signals together.
If at all places a local oscillator synchronized
to an atomic clock like DCF-77 or MSF is used to
mix the LF-band down to AF, then a simple FM link
on 2m or 70cm would do this job. Then the antenna
could virtually be turned around in any direction
after reception.
Unfortunately, I don't have the time to build an
amplifier and a LF-Antenna.
73 de Klaus, DJ5HG
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