Am 21.04.2019 um 01:33 schrieb John Fisher:
A quartz piezoelectric crystal converts electrical energy to mechanical energy
and vice versa.
It won't convert electrical energy into an electromagnetic wave by itself.
Magnetostrictive material such as Terfenol-D will convert mechanical vibrations
into a fluctuating magnetic field.
This can generate an electromagnetic wave directly using the homopolar effect.
A piezoelectric transducer can be used to mechanically drive magnetostrictive
material to produce an EM wave.
Efficiency is several orders of magnitude greater than a wire antenna enabling
practical portable VLF transmitters.
73 de VA3VVV
Hi John,
a most interesting approach! Is it more a theoretical idea or do you
have some details or papers about practical realisations? Up to now I
associated with Terfenol-D heavy transducers for under water Sonar with
electromagnetic excitation and with the homopolar effect a combination
of low voltages and high currents ...
Due to the swing of a piezoelectric element being much less than the
swing of a magnetostrictive element I suppose one has to use several
stacked piezoelements for excitation. Another task could be to make a
non-elastic force-fit connection between those partners being rather
different in mass and to fix the whole unit at the surrounding
structures. But I suggest we should discuss this directly - the matter
seems to be rather OT for the lf reflector ;-)
By the way: impressive pictures on your qrz.com site!
73,
Tom, DK1IS
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