> Tom has indicated that modelling programs report vastly incorrect numbers
in
> terms of the Q of a solenoid inductor at tens or hundreds of Megahertz.
> This is true. Three dimensional modelling programs were not made for that
> task; they are made for modelling the electrical properties of physical
> structures such as are used at tens of GHz and up, and are generally
planar
> or pseudo-planar. I do not know of any modelling tool that professes to
> properly model that inductor. And why would I want such a tool? It is an
> easy parameter to measure, and then use a macro model in simpler software,
> why would anybody with good judgement attempt the task?
Resistors are equally easy to measure, but resistor models are provided so
that more complex circuits containing resistors can be modeled. The same
should be true of solenoid inductors.
Having spent the day commuting to Raleigh NC from the Boston area, I've not
canvassed any modeling tool vendors - and thus cannot dispute the "none can
model solenoid inductors" claim. But you make an important point: if a
modeling tool allows one to provide models of user-defined-devices, then one
can home-brew an accurate model of a solenoid inductor and model with
confidence.
> There is no cure all. I have encountered amplifiers that required
parasitic
> suppressors, and I have encountered amplifiers that were destabilised by
> same. I have never encountered an amplifier that a model showed as stable
> that oscillated. And every amplifier that I've seen oscillate has been
> predicted to do so, or be close to doing so, via modelling.
Are you using a commercial modeling program, or rolling your own?
73,
Dave, AA6YQ
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|