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From: "Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
Date: Wed, 31 Aug 2016 15:53:25 -0400
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Subject: Re: [geda-user] Microwave PCB layout simulation or How to eat all
 your processing power in 3 easy steps
To: gEDA users mailing list <geda-user AT delorie DOT com>
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On Wed, Aug 31, 2016 at 1:13 PM, Larry Doolittle
<ldoolitt AT recycle DOT lbl DOT gov> wrote:
> 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.

That is what I expected from it.

> I've put OpenEMS on my list to look at.  Unfortunately, my list is
> pretty long.

Are you looking at other open source EM solvers? I made a list of them
(with notes) myself if you want to compare lists?

>> > 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.

I know. The guys I am working with here are modelling the mechanics of
the middle ear. Fundamentally it is an impedance matching transformer
from air to fluid but there are all manner of bones in there and etc.

I thought soldermask issues were why most of the microwave and other
RF hardware I have seen has no soldermask.

I am writing to the openems maintainer to find out what the limits and
etc are of openems.

>   - Larry

- Evan

-- 
Home
http://evanfoss.googlepages.com/
Work
http://forge.abcd.harvard.edu/gf/project/epl_engineering/wiki/

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