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Re: LF: NEW quarz resonated VLF antenna

To: [email protected], [email protected]
Subject: Re: LF: NEW quarz resonated VLF antenna
From: DK1IS <[email protected]>
Date: Sun, 21 Apr 2019 23:27:57 +0200
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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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