On Sun, 29 Mar 2026 13:15:32 -0400, joegwinn@comcast.net wrote:
On Sun, 29 Mar 2026 12:24:30 -0400, legg <legg@nospam.magma.ca> wrote:
On Sat, 28 Mar 2026 07:42:46 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Jan Panteltje <alien@comet.invalid> wrote:
[...]
What are the benefits of using a shock-resistant antenna in Casio watches?
i?4 How does the amorphous material in Casio antennas enhance radio signal
reception?
Could it be some sort of rubber-based ferrite (like the magnetic rubber >>>> strips around fridge doors)? Ordinary ferrite might shatter if you
dropped the watch but rubber ferrite woudn't - it could also be moulded >>>> into a shape that would better fit the watch case or perhaps have better >>>> signal-gathering properties.
The industry uses the term amorphous with no rigour.
By definition it describes only a 'mixture' of materials. These
could have magnetic or other properies.
Most compressed dust cores meet this definition, as they depend
on chemical binders and fillers to establish magnetic density
and mechanical integrity.
It has also been used to describe bonded magnetic particles
in flexible media, treated during the curing process for
particle polar alignment or other useful characteristics.
The term has recently been used to describe alloyed metal strips,
for no apparent reason, other than to describe a mixture of
components in the alloy - something that has always been taken
for granted.
In industry, _amorphous_ has a precise meaning when speaking of
metallic alloys, that there is no crystalline structure, that it has
the (lack of) structure of a glass. So it's brittle but quite
flexible if thin. So if a piece of such strip is bedded in something
soft and flexible, the strip can be quite resistant to shock and
vibration.
Joe
While metals are usually associated with ductile properies, alloys
are created to increase strength and rigidity - also brittleness.
In nanocrystaline alloys, the crystal structure of an alloy's particle
is recognized, however: the manufacturing method attempts to
distribute these particles in a disordered form - hence the
improper use of the amorphous term (see the dictionary).
These brittle materials' magnetic properties suffer if deformed after
mrf and so tend to be created in as close-to-end-use form as is
possible. Machining, as with glass, is difficult.
Toroidal shapes formed by strip rolls can lose a half order of
magnitude in permeability, simply due to later coil-winding
pressure, or end-use mounting forces.
The simplest physical demonstration of the material's mechanical
properties is to crush an 'amobead' with pliers. These depend on
a thin epoxy coating for mechanical integrity. Larger parts will
have a plastic or metal/fibre casing, with mechanical buffering
properties.
RL
Yes, a ferrite rod antenna is widely considered the best practical choice for receiving a 60 kHz plane wave (such as the WWVB or MSF time signals) due to its high selectivity and compact size.
At 60 kHz, a full-sized half-wave dipole would be approximately 2.5 kilometers long, making traditional wire antennas highly impractical for most users.
Why Ferrite Rods Excel at 60 kHz
High Selectivity (Q Factor): Ferrite rods are "sharply tuned" resonant devices. This allows them to reject nearby electrical noise and interference from computers or power supplies that often plague the Very Low Frequency (VLF) band.
Magnetic Field Sensitivity: Unlike wire antennas that respond to the electric field (which is more prone to local noise), ferrite rods respond to the magnetic component of the radio wave.
Compact "Effective Area": The ferrite material concentrates magnetic flux, making a small rod perform like a much larger air-core loop.
Directionality: You can rotate the rod to "null out" local interference or maximize the signal from the transmitter.
-Google AI
Jeff Layman <Jeff@invalid.invalid>wrote:
On 31/03/2026 00:30, someone wrote:
Yes, a ferrite rod antenna is widely considered the best practical choice for receiving a 60 kHz plane wave (such as the WWVB
or MSF time signals) due to its high selectivity and compact size.
At 60 kHz, a full-sized half-wave dipole would be approximately 2.5 kilometers long, making traditional wire antennas highly
impractical for most users.
Why Ferrite Rods Excel at 60 kHz
High Selectivity (Q Factor): Ferrite rods are "sharply tuned" resonant devices. This allows them to reject nearby electrical
noise and interference from computers or power supplies that often plague the Very Low Frequency (VLF) band.
Magnetic Field Sensitivity: Unlike wire antennas that respond to the electric field (which is more prone to local noise),
ferrite rods respond to the magnetic component of the radio wave.
Compact "Effective Area": The ferrite material concentrates magnetic flux, making a small rod perform like a much larger
air-core loop.
Directionality: You can rotate the rod to "null out" local interference or maximize the signal from the transmitter.
-Google AI
That's what the theory might say, and perhaps in practice too. However,
My watch has shown the "wrong" time in the morning when I looked at it
after being right when I've gone to bed. This is what the Junghans
manual for the watch states:
"Junghans radio-controlled watches synchronise themselves with the DCF
77 time signal transmitter every day. This is done during the night at
02.00 and 03.00 hours. If interference (e.g. from thunderstorms, nearby >electrical equipment, light dimmers etc.) makes it impossible for the
time signal to be picked up at the first attempt, the Junghans >radio-controlled watch will automatically make further attempts. Time >synchronisation can also be carried out manually (e.g. in an area with >better reception conditions) by using the watchrCOs transmitter call button."
It confirms that reading of the DCF time signal can be interfered with.
What I am unsure about is whether or not the signal can not only be >interfered with so it /cannot/ be read, but /could/ be read from a
source other than DCF 77 and misinterpreted. At least twice I have been >wearing the watch during the afternoon and it has shown the wrong time
when I've looked at it (it was correct in the morning). If the watch is >supposed to synchronise only between 02.00 and 03.00, why did it change
to the incorrect time during the day?
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