Re: [SI-LIST] : the old high-frequency return current model

C Deibele (deibele@fnal.gov)
Mon, 04 Oct 1999 11:24:26 -0500

> Other field solvers, such as the Maxwell 2D Extractor, from Ansoft, will
> solve LaPlace's equation to get the capacitance matrix elements, and
> separately, Ampere's equation, to get the high frequency current
> distribution, and then the magnetic fields, and then the inductance matrix
> elements. The boundary condition it uses is that at high frequency, skin
> depth is so small, there is no field inside the conductor and it behaves
> like a perfect conductor, so the B field is only tangential at the surface,
> no normal component. I have compared the two results- Hyperlynx's and
> Ansoft's tool- and the agreement is within 2% across a wide range of aspect
> ratios.
>
> In addition, the Ansoft tool, for example, will separately, if requested,
> solve the Helmholtz equation (frequency domain solution for J and B) and
> extract the current distribution inside the conductor (using FEM), at a
> specified frequency. This will allow you to see the actual current
> distribution inside the conductor, as frequency is varied. The plots I sent
> around a few weeks ago were created using this tool. That's why the Ansoft
> tool is often referred to as the "Rolls Royce of field solvers".
>

I actually had lots of problems with Ansoft's program. If phase is
of any importance, they have a lousy program for calculating it. I have
been working with Sonnet software -- they have a program like Ansoft's
and it works great. It isn't perfect, mind you, but it is much much
better.
I don't know about the cost differences though. It all boils down to
what the particular program uses for the MoM as green's functions.
Ansoft
is sort of new to the business of MoM for enclosed structures. I think
in awhile they will have a more mature product. Not yet though.

Definitely try out sonnet's program. www.sonnet.com i believe.

Craig

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