Distinct difference between schematic&EM simulation in M
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.
what is the software you used?
Please post the project file also.
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.
Here is it.
Here is the whole project settings.
Pls check it.
If there is something wrong,please let me know!
Thanks.
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.
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
Loucy,AL0117,
Happy new year!
Thank you for your help!I will correct my settings and try later!
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
Hi, STD again!
I've used Ie3d library to design your filter in few minutes..
look at results.
Regards,
eirp
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
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
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