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Date: Wed, 31 Aug 2016 10:13:20 -0700
From: Larry Doolittle <ldoolitt AT recycle DOT lbl DOT gov>
To: "Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
Subject: Re: [geda-user] Microwave PCB layout simulation or How to eat all
 your processing power in 3 easy steps
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Evan -

On Wed, Aug 31, 2016 at 12:45:37PM -0400, Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com] wrote:
> On Wed, Aug 31, 2016 at 2:10 AM, Larry Doolittle <ldoolitt AT recycle DOT lbl DOT gov> wrote:
> > Yes, some background.  Urmel, Superfish, meep, S parameters,
> > waveguides, series solutions.
> Ok cool. Meep was my 2nd choice. OpenEMS had more stuff related to
> what I expected users here to want though. (plus it didn't use scheme)
> What was your impression working with meep? Why did you choose it? How
> hard was it to validate it's output?

Meep looks pretty.  I had a hard time doing anything useful with it.
I've put OpenEMS on my list to look at.  Unfortunately, my list is
pretty long.

> > And I recommend trying to keep expectations low, at least at first.
> Because it is hard to get things going or because it is very easy with
> FEM to make fancy graphs and etc that look cool/right but are horribly
> wrong?

Connecting to reality can be hard.  So many assumptions about
e.g. materials parameters go into the calculations.  What's the
dielectric constant of soldermask?  How does the software deal with
outgoing radiation, even if the design goal isn't to build an antenna?
A realistic model can get very complicated very fast.  Complicated
3D geometries push computational limits, leading to either long
run times or poor convergence, or both.

  - Larry