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Oh, because I want to make sure the simulation is still accurate if I don't know how to simplify the problem and just give the whole thing to the simulator. Also, most of the real PCB I work with are 4 layers without possible simplification, and I see similar resonance at higher frequency from...
Hi Volker, sorry to bug you again, I ran into a new issue with the same case. Last time, I did the simulation based on a 2 metal layer board. The original board has 4 metal layers, of which the bottom 3 layers are just solid ground planes connected through vias. So I deleted the bottom two to...
Oh...I always ignored the copper surface roughness, I looked at the table you attached, and don't quite understand the first column, how do I know which foil type my board is using? Should the PCB vendor have the info or is there something general I can assume?
Um...I'm not sure if I understood it correctly, I thought RO4003 is the dielectric, and the copper is on top of the Rogers material, not inside. The copper trace is 1.5oz, which translates to 52.5um. I don't think there's other metal on top of it.
For the S21, I meant the measurement has more...
I see. I get pretty good match b/w simulation and measurement for S11 now. I still have some issue with S21, the simulated value is always higher than the measured value. Since S11^2+S21^2 != 1 in reality because of losses, I think the simulation didn't catch all the losses that present in the...
Hi Volker,
Thanks, I looked at your model for discontinuity and it's really inspiring! Now I can see how extra L or C makes a difference here. I just have a few more questions.
1) When I place the ports slightly inside, not at the edge of the small rectangles, the amplitude of S11 is lower...
Hi Volker,
Thank you so much for all these explanations. I'll spend more time looking at your comments and try a few things as you suggested. Just wondering, did you attached the modified workspace? I wanna see how you played with the schematic, but I don't see the attachment from my end...
Hi, Volker,
Thanks a lot for your help. Here's some more info regarding the issues you mentioned:
1. The extra piece of metals were in the layout when I got the file. I think it corresponds to the actual shape of the fabricated board. There are two pieces of ground/copper stick out in the...
You can get permittivity through conductivity. Just look up the formula that relates real/imag part of permittivity with real/imag part of conductivity. The formula is available in the advance electromagnetics book by Balanis. Otherwise, you may also find some thesis work on graphene simulation...
Thanks, these are awesome materials! I'm focusing on extracting PCB boards using Momentum, and the port setup is a big challenge since I realize I'm getting different results just by setting up the ports differently. Actually I'll just post one of my examples below. Maybe you could shed some...
I still haven't figured out what I did wrong here...I've attached my workspace, and I've run a few cases with different port setups, could you please take a look at it and tell me what I did wrong to get the unphysical result? Thanks you very much!
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Hi, I've attached my...
I see. The weird thing is I keep getting the +20dB S11. Let me spend more time looking into it. If I still can't figure out what's wrong, I'll attach a workspace, maybe there's some stupid mistake I've made.
Thanks a lot!
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