Date: Sat, 20 Apr 2019 23:33:19 +0000 (UTC)
From: John Fisher <johnfish837@yahoo.ca>
To:  <rsgb_lf_group@blacksheep.org>, <rsgb-lf-group@groups.io>
Message-ID: <196929709.3434980.1555803199918@mail.yahoo.com>
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Subject: Re: LF: NEW quarz resonated VLF antenna
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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

--------------------------------------------
On Sat, 4/20/19, DK1IS <DK1IS@kabelmail.de> wrote:

 Subject: Re: LF: NEW quarz resonated VLF antenna
 To: rsgb_lf_group@blacksheep.org, rsgb-lf-group@groups.io
 Received: Saturday, April 20, 2019, 5:15 PM
 
 
     Am 19.04.2019
 um 17:28 schrieb Clemens
       Paul:
       
 
       Do you think it is possible
 for a more
         true comparison to compare the quartz resonated wire
 antenna
         
 
         against he same wire resonated conventionally by an
 inductor
         regarding field strength and 3dB BW?
         
 
     Hi Clemens and group,
     here is the promised extension of my tests, for
 better
       comparability merged with the first results (my post
 on the
       reflector from 20190418):
     Having no VLF quartz yet, I made some preliminary
 tests with a
       randomly available HC-6-U quartz, QRG 2434 kHz,
 wavelength 123 m.
 
     
     TX: Sythesizer Schomandl MG100M, 300 Hz ... 100
 MHz, smallest
         step 0.1 Hz, Ri = 50 Ohms, P = 10 dBm, output tied
 to first leg
         of quartz, alternatively direct to the antenna
 wire
 
       RX: Perseus SDR with an active rod antenna on
 my garage, fed
         by a solar system, no external wire connections,
 air-line
         distance 100 m to my shackAntena wire: 2 m
 or 4 m, laid out in the shack, tied to second
         leg of quartz, alternatively direct to the TX
 outputalternatively antenna
 wire only
           resonated by two roller plus one fixed inductors
 in series,
           fed directly from the TX output 
 
       
     Results with 2 m antenna wire:
     with quartz resonator: fres = 2,433,908.8 Hz, RX
 level at
         resonance = - 63,1 dBm, - 3dB-bandwidth = 48.3 Hz
 resulting in Q
         = 50391without quartz resonator: RX level =
 - 85,4 dBm resulting in a
         gain of 22.3 dB with quartzcomparision: my
 13 m T-Marconi with top load 4 x 33 m, tuned
         to 2434 kHz and fed by the synthesizer with 10 dBm
 results in a
         RX level of - 32.1 dBm ;-)with inductive tuning at 2,434,000 Hz:
           RX level = - 60.1 dBm resulting in a gain of 3dB
 compared with
           quartz. -3 dB-bandwidth = 249 kHz resulting in a
 loaded Q =
           9.8
 
       
     Results with 4 m antenna wire: 
 
     
     with Quartz resonator: fres = 2,433,773.6 Hz, RX
 level at
         resonance = - 59 dBm. - 3 dB-bandwidth = 49.4 Hz
 resulting in Q
         = 49376without quartz resonator: RX level =
 - 75.4 dBm resulting in a
         gain of 16.4 dB with quartzwith indctive tuning at 2,234,000 Hz: RX
           level = - 57.3 dBm resulting in a gain of 1.7 dB
 compared with
           quarz. - 3 dB-Bandwidth = 390 kHz resulting in a
 loaded Q =
           6.2
     With all tests there was no additional resistive
 matching at the
       TX output. The tests at resonance showed the usual
 unbalance
       between lower and upper - 3 dB-points. With L-tuning
 the upper is
       further away from the resonance frequency than the
 lower. With
       quartz-tuning this effect is contrawise and of course
 absolutely
       much lesser accented. At a first glance L-tuning
 offers advantages
       due to its comparable huge bandwidth and the higher
 fieldstength
       at the RX site but this could shrink if you really go
 down to VLF
       frequencies, very short antennas and short distances.
 According to
       the author´s claims the quarz resonated system is
 usable for short
       range communication only and there the Q of L-tuned
 antennas will
       also grow to high values as well as the losses in the
 tuning
       circuit.
     As soon as my ordered XTALs will arrive I´ll make
 further tests
       in the 4 kHz-range. If the results happen to differ
 very much from
       the preceding tests at 2.4 MHz I´ll report about
 it.
     73 es Happy Easter,
     Tom, DK1IS