[SI-LIST] Re: HFSS solution issue

Hi, to maximize the physical memory usage, you can go to /maxwell/config/ 
directory, then open the file pref.ini with notepad or wordpad. In the file, 
add the following:

DIRECT_SOLVER MemLimitSoft  131072 (max.=70% of your physical memory, in 
kilobytes)
DIRECT_SOLVER MemLimitHard  131072( max.=120% of your physical memory, in 
kilobytes)

Regards,
Xin




Xin Wu
Ph.D student,
University of Maryland, College Park
Http://www.wam.umd.edu/~xwu






>From: "Chandrasekhar Arun" <achandra@xxxxxxx>
>Reply-To: achandra@xxxxxxx
>To: <Dan_Swanson@xxxxxxxxxxxx>, 
><mike_bihan@xxxxxxxxxxxx>,<si-list@xxxxxxxxxxxxx>
>Subject: [SI-LIST] Re: HFSS solution issue
>Date: Fri, 24 Jan 2003 11:45:57 +0100
>
>
>Hello Dan and all HFSS users,
>       Excellent comments from Dan and it really summarises what every HFSS =
>new user needs to know reg. solving his/her model. A few points from my =
>experience
>1. My primary application with HFSS is solving chip-package =
>interconnects and I use a delta-S of 0.005. This number is not =
>sacrosanct, but when coverted to dB is -0.043 dB for insertion loss and =
>-46 dB for return loss
>IL=3D20log10(1-0.005) and RL=3D20log10(0.005)
>The key is finding an optimum between solution accuracy and time. I =
>expect my structures to have an insertion loss of about 1 dB at 5 GHz =
>and it is Ok for me if my HFSS results are 1.043 or 0.957 dB. However if =
>you are trying to extract the S-parameters of a low-loss short line, =
>maybe this error is too high. However, already to achieve 0.005 eroor I =
>have to live with about 25000 tetrahedra and this takes a few hours to =
>simulate for 20 points and there is no way I can think of delta-S lower =
>than 0.005!
>2. If you are usinh HFSS at low frequencies, remembet to Solve Inside =
>Metals !
>3. To compare your results with VNA measurements always de-embed and =
>re-normalise with 50 ohms
>
>one question
>does anyone know how you can manipulate the amount of memory used by =
>HFSS while solving in the RAM and the disk? I have 1GB of RAM, still =
>HFSS always swaps some data with the disk. I remember that the deafult =
>is 70% RAm and 30% dis, but I do not see this always!
>Regards
>  =20
>Arun Chandrasekhar
>PhD Student: RF Packaging     =09
>IMEC | MCP/MaRS Group =09
>Phone:         +32 16 28 82 28 =09
>Fax:   +32 16 28 10 97 =09
>Email:         achandra@xxxxxxx <mailto:achandra@xxxxxxx>  =09
>Seeds for Tomorrow's World <http://www.imec.be/>  =09
>  =20
>IMEC, Kapeldreef 75, 3001 Leuven, Belgium   |  Phone:+32 16 28 12 11  =
>Fax:+32 16 22 94 00  |   Website: www.imec.be <http://www.imec.be/>=20
>
>
>
>This e-mail and/or its attachments may contain confidential information. =
>  It is intended solely for the intended addressee(s).
>Any use of the information contained herein by other persons is =
>prohibited.  IMEC vzw does not accept any liability for the contents of =
>this e-mail and/or its attachments.=20
>
>
>-----Original Message-----
>From: Swanson, Dan [mailto:Dan_Swanson@xxxxxxxxxxxx]
>Sent: Thursday, January 23, 2003 17:23
>To: 'mike_bihan@xxxxxxxxxxxx'; si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: HFSS solution issue
>
>
>
>
>Bi, Han
>
>I think you are a little confused on how the solution setup goes.
>
>Adaptive Single Frequency can be run by itself or it
>is the starting point for a Frequency Sweep.
>
>So you adapt the mesh at some frequency, typically the highest
>freq you are interested in. Then you start the frequency sweep
>using that adapted mesh. So the mesh is "overkill" for the low
>freqs and just right for the high freqs. Knowing this, if you
>are trying to cover many octaves in frequency, then maybe
>several runs using different adapt freqs is more efficient.
>
>So in the setup menu you select both the Single Freq Adapt
>and the Freq Sweep you want at the same time. The software then
>does both.
>
>If you run a Discreet Sweep, results should be fine. A Fast Sweep
>tries to derive the result from the minimum number of discreet=3D20
>freq solutions. Watch out for the both ends of the sweep range
>and always check the results at least once with a discreet sweep.
>If you ask for a very wide Fast Sweep range, the software often
>suggests that you break it up into smaller segments.
>
>As to number of adapts, that is very tricky. Basically you need
>to identify the key parameter in your analysis and figure out
>what it takes to get there. For example, I do a lot of resonators.
>So I look at convergence of resonant frequency as function of meshing
>parameters. Remember this is very general purpose software, you always
>know more about you particular problem than the developer or the =3D
>software.
>You have to use that knowledge to guide the software to the right
>solution.
>
>Using the default settings, the starting mesh in HFSS is very coarse.
>I typically set LAMBDA_REFINE_TARGET (system variable) to .02 or .033
>Refinement percentage to 40% (default is 20%).  And maybe run 5 to 10
>adapts. I set Delta-S limit to 1e-6, Delta-S achieved is very problem
>dependent and does not always imply absolute convergence. Of course
>you are looking for a convergence curve that is a nice smooth =3D
>parabolla.
>
>The geometrical resolution in your model will also affect convergence.
>I tend to draw cylinders, etc kind of coarse, 8 or 12 sides to a =3D
>cylinder.
>I do this to speed things up. But sometimes if you make things too =3D
>coarse
>the convergence curve will oscillate, or you may converge to the wrong
>final value. For example, look at impedance of a coax line as a =3D
>function
>of how many segments you use to define the cylinders.
>
>All this is in my new book, coming out in May 2003:
>
>http://www.artechhouse.com/default.asp?Frame=3D3DBook.asp&Book=3D3D1-5805=
>3-3=3D
>08-6&Cou
>ntry=3D3DUS&Continent=3D3DNO&State=3D3DMA
>
>
>Best regards,
>
>
>Dan
>
>Dan Swanson                    EMAIL:  d.swanson@xxxxxxxx
>Forem USA                              PHONE:          978-834-4085
>37 South Hunt Road             FAX:    978-388-7077
>Amesbury, MA  01913
>
>
> > -----Original Message-----
> > From: Bi Han [mailto:mike_bihan@xxxxxxxxxxxx]
> > Sent: Thursday, January 23, 2003 10:52 AM
> > To: List` Si
> > Subject: [SI-LIST] HFSS solution issue
> >=3D20
> >=3D20
> >=3D20
> > hi, ansoft guies:
> >=3D20
> > There is one simple question about HFSS.
> >=3D20
> > Since Adaptive 'Single frequency' analysis will allow users=3D20
> > to setup 'Requested Passes', what number will be suitable? I used 7.
> >=3D20
> > However, issues come up!
> > The results,obtained by 'Single Frequency', differs greatly=3D20
> > from 'Sweep' analysis=3D20
> >=3D20
> > results? Because of the higher accuracy of 'Single frequency'=3D20
> > analysis, I prefer it than sweep one. (Actually,sweep results=3D20
> > is the Pass 1 results on Single Frequency analysis.)
> >=3D20
> > Then, what value does 'sweep' analysis have, with so poor=3D20
> > accuracy, whose mesh will not be refined. In another way, in=3D20
> > which way should we treat the data from 'sweep analysis'?
> >=3D20
> > Sincerely,
> > Bi, Han
> > Sjtu, EMLAB
> >=3D20
> >=3D20
> >=3D20
> > ---------------------------------
> > Do You Yahoo!?
> > =3D
>"=3DBF=3DEE=3DBF=3DEE=3DB8=3DDF=3DB9=3DF3=3DB5=3DE4=3DD1=3DC5=3DA3=3DAC=3D=
>B5=3DE3=3DBB=3DF7=3DB2=3DCE=3DBC=3DD3=3DC6=3DFB=3D
>=3DB3=3DB5=3DB5=3DF7=3DB2=3DE9!"
> >=3D20
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