Re: Yttrium iron garnet

john larkin <jl@650pot.com> 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guessing they've been completely superseded by now to get to ever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.
 
One can't modulate a hundreds-of-mA electromagnet very fast.
 
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.

And far, far noisier than the best YIGs.

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

It isn’t, actually, at least over a restricted range. If the resonator
obeys a differential equation, you can modulate its resonance much faster
than f_0/Q by changing L or C.

Resonators with significant time delay, such as a long piece of coax,
aren’t as friendly that way.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics