Re: Yttrium iron garnet

On 31/05/2024 12:04 am, john larkin wrote:

On Thu, 30 May 2024 11:03:19 GMT, Glen Walpert <nospam@null.void>
wrote:
 

On Thu, 30 May 2024 09:14:58 -0000 (UTC), Cursitor Doom wrote:
>

On Thu, 30 May 2024 15:45:21 +1000, Bill Sloman wrote:
>

On 30/05/2024 3:37 am, john larkin wrote:

On Wed, 29 May 2024 17:12:21 -0000 (UTC), Cursitor Doom
<cd999666@notformail.com> wrote:
>

On Wed, 29 May 2024 13:52:34 +1000, Bill Sloman wrote:
>

Yttrium iron garnet tuned oscillators were around back then, but
their 2GHz to 8GHz range was too high for me to count with the
integrated circuits around then - we had to go the Gigabit Logic's
GaAs parts to get to 800MHz, and that became the unique selling
point of the system.

>
YIG oscillators were quite the thing back in the day, but I'm
guessing they've been completely superseded by now to get to ever
higher frequencies. Seems we've gone from -

>
This misses Jan Panteltje's thread "Small magnetic tunable filter for
6G and beyond" which is about Yig being used today.

>
That article makes it seem like YIG is some revolutionary, new, emerging
technology!

>
Use of YIG filters as a replacement for varactor tuning could turn out to
be significant.  2022 Microwave Journal article:
>
<https://www.microwavejournal.com/articles/37980-reinventing-yig-
technology-for-microwave-filter-applications>

 The VIDA oscillators still look like giant expensive power hogs. They
don't specify modulation bandwidth on the data sheets that I see, but
it must be terrible.

https://www.nature.com/articles/s41467-024-47822-3
makes quite a lot of fuss about them not being power hogs.

One can't modulate a hundreds-of-mA electromagnet very fast.

In fact they tweak quite a compact permanent magnet stack. How fast they can do it isn't discussed (or at least if they did I didn't notice it).

An LC osc with a varicap is a more sensible VCO. Narrowband, one can
varicap a coaxial ceramic resonator, or a PCB ring oscillator, or
something. Cheap and fast.

Varicaps are horribly non-linear. Narrow-band is always easier than wide-band, but the YIG tuning scheme is good for at least a factor of two frequency range and once you've got that you can use counters to go down from there until you run out of dividers

Of course, it's inherently difficult to modulate a high-Q resonator
fast, even without an electromagnet in the way.

You don't need an electromagnet to get the fields required. You may want a non-conducting permanent magnet to proved the bulk of the field - or it might be enough to split your magnetic path into lots of parallel wire magnets insulated from one another. There are ferrite permanent magnets which aren't all that electrically conductive.
This reads more as if you don't want it to work - it's the sort of contribution that gets people chucked out of brain-storming sessions.
--
Bill Sloman, Sydney