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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: Thu, 1 Sep 2016 00:07:28 +0000
Message-ID: <CAM2RGhSpi4dLqKQ_X+Uqmkf-ApqBiy0=gMpGLWWnVvoEhorFTA@mail.gmail.com>
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 9:39 PM, Larry Doolittle
<ldoolitt AT recycle DOT lbl DOT gov> wrote:
> Evan -
>
> On Wed, Aug 31, 2016 at 03:53:25PM -0400, Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com] wrote:
>> On Wed, Aug 31, 2016 at 1:13 PM, Larry Doolittle <ldoolitt AT recycle DOT lbl DOT gov> wrote:
>> > 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.
>
> For the long lines, yes, depending on the designer, but eventually
> those lines usually touch chips.  And high-speed serial lanes (with
> the interesting frequency range now going up to 40 GHz) usually don't
> have soldermask stripped off.

At those frequencies I would actually think the chip would be supplied
as bare die and wire bonded.

>> I am writing to the openems maintainer to find out what the limits and
>> etc are of openems.
>
> Sounds good.
>
>    - Larry



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

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