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STD
Joined: 10 Dec 2003
Posts: 78
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 25 Dec 2003 5:49 Distinct difference between schematic&EM simulation in M |
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Hi all,
Filter simulating.
Freq. range is 7-24G.
In schematic simulation 1-12G is passband,and 16-24G is stopband.
But in EM simulation,1-12G is stopband.
This has puzzled me!
I will post simulation result later.
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loucy
Joined: 26 Aug 2001
Posts: 423
Helped: 10
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| 25 Dec 2003 14:04 Re: Distinct difference between schematic&EM simulation |
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what is the software you used?
Please post the project file also.
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STD
Joined: 10 Dec 2003
Posts: 78
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| 26 Dec 2003 14:08 Re: Distinct difference between schematic&EM simulation |
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The result is ploted in the picture.
I use MWO to simulate.
And the project is the same as I posted several days before.
I only shorted the edge port's length to the shortest length.
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STD
Joined: 10 Dec 2003
Posts: 78
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| 26 Dec 2003 14:22 Re: Distinct difference between schematic&EM simulation |
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Here is it.
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STD
Joined: 10 Dec 2003
Posts: 78
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| 29 Dec 2003 16:33 Re: Distinct difference between schematic&EM simulation |
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Here is the whole project settings.
Pls check it.
If there is something wrong,please let me know!
Thanks.
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loucy
Joined: 26 Aug 2001
Posts: 423
Helped: 10
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| 30 Dec 2003 16:40 Re: Distinct difference between schematic&EM simulation |
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The mesh in the EM_Filter is not fine enough to capture the thin microstrip line. If you select "show mesh", you can see that the thin line is not meshed, thus there is no metal connection between the input and output.
In the schematic setup, the substrate is not defined for the elements (MTEE etc.) Check the manual and make sure the elements are properly defined before doing the simulation.
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AL0117
Joined: 25 Jul 2003
Posts: 230
Helped: 8
Location: dracu-la-nd
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| 31 Dec 2003 10:01 Re: Distinct difference between schematic&EM simulation |
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Hi STD,
Loucy is right, the mesh is not set in a right way, so you don't have continuous metal and this is what you see on your graph. Normally 1/100 wavelength for the cell dimention is a good starting point, I think you can mesh with a cell size of 100um
But frankly speaking, the linear simulated filter doesn't look pretty good. The return loss in the passband is very poor --> your passband has quite big ripple.
With the linear simulation, you don't take in account the coupling between the arms of the filter. If you want more accurate linear simulation, use the coupled line model for the 6 arms. Take a look in the examples folder
\Circuit Design Types\Filters\18Ghz_LPF.emp and 8GHz_LPF.emp also for the XModel_BandPass.emp .
If you are using x models, be shore that you filled the database for the specific Er.
Please send PM to me if I can help further.
rgds, Al
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STD
Joined: 10 Dec 2003
Posts: 78
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| 31 Dec 2003 17:55 |
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Loucy,AL0117,
Happy new year!
Thank you for your help!I will correct my settings and try later!
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eirp
Joined: 11 Dec 2001
Posts: 807
Helped: 9
Location: Phase center
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| 01 Jan 2004 23:32 Re: Distinct difference between schematic&EM simulation |
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Yes, mesh in MWO is bad.
I'm attaching results of quick (hope substrate parameters was OK) analysis your filter performed by IE3D.
Rgz,
eirp
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eirp
Joined: 11 Dec 2001
Posts: 807
Helped: 9
Location: Phase center
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| 02 Jan 2004 12:14 Re: Distinct difference between schematic&EM simulation |
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Hi, STD again!
I've used Ie3d library to design your filter in few minutes..
look at results.
Regards,
eirp
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STD
Joined: 10 Dec 2003
Posts: 78
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| 02 Jan 2004 16:48 |
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Thank you,eirp!
Can IE3D do further optimization?Because the performance doesn't meet the requirement.
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eirp
Joined: 11 Dec 2001
Posts: 807
Helped: 9
Location: Phase center
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| 02 Jan 2004 17:31 |
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| STD wrote: |
Thank you,eirp!
Can IE3D do further optimization?Because the performance doesn't meet the requirement. |
Hi, STD!
Of course, it can!!
What are exactly the requirements? Results above doesn't meet it?
Regards,
eirp
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STD
Joined: 10 Dec 2003
Posts: 78
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| 03 Jan 2004 16:45 |
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Hi eirp,
The spec :1-12G IL<3dB,ripple<2dB
16-24G attenuation<-40dB.
B.T.W. Is your simulation in IE3D is EM simulation?
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eirp
Joined: 11 Dec 2001
Posts: 807
Helped: 9
Location: Phase center
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| 03 Jan 2004 20:18 |
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| STD wrote: |
Hi eirp,
The spec :1-12G IL<3dB,ripple<2dB
16-24G attenuation<-40dB.
B.T.W. Is your simulation in IE3D is EM simulation? |
Hi, Std,
is this result better now?
Simulation is of course EM.
Rgz,
eirp
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STD
Joined: 10 Dec 2003
Posts: 78
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| 04 Jan 2004 12:33 |
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Thank you, eirp!
It's perfect!
Can you upload the filter's dimension?
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eirp
Joined: 11 Dec 2001
Posts: 807
Helped: 9
Location: Phase center
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| 10 Jan 2004 19:54 |
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| STD wrote: |
Thank you, eirp!
It's perfect!
Can you upload the filter's dimension? |
Of course, here you have (file for IE3D and .dxf)
I've used substrate with h=0.254mm and epsr=9.9
It's very thin, I suppose results needs to be recalculated using your sub.
Regards,
eirp
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