I am trying to design a microstrip bandpass filter in ADS with a center frequency of 2.4GHz and a fractional BW of 10%. My results from the schematic look great: enter image description here

When I move to the layout and EM simulation, my results look nothing close to a bandpass filter. I am not sure if it is something with my setup or the physical layout. The schematic and layout is shown below: enter image description here

enter image description here

The results from the EM simulation are here: enter image description here

I was thinking it could be with how close the spacing is between the coupled lines, but if anyone can point me in the right direction it would be greatly appreciated

  • \$\begingroup\$ This is out of my field. but a guy that is true scientist makes those lines little bit different, surely there are also exact formulas, but I was not his student. Look for some his examples: s53mv.s5tech.net/cavity/cavity.html s53mv.s5tech.net/zifssb/block.html s53mv.s5tech.net/zifssb/lscband.html \$\endgroup\$ Commented Dec 27, 2020 at 0:24
  • \$\begingroup\$ I don't have the resources to use a cavity \$\endgroup\$
    – user267451
    Commented Dec 27, 2020 at 0:32
  • 1
    \$\begingroup\$ Your first and last couple sections look like they have no gap at all. I don't know why, but that is almost surely the problem. \$\endgroup\$
    – The Photon
    Commented Dec 27, 2020 at 0:41
  • \$\begingroup\$ Make sure the mesh size in your EM simulation is smaller than the 50 um gap you are trying to model. \$\endgroup\$
    – The Photon
    Commented Dec 27, 2020 at 0:44
  • \$\begingroup\$ Only the 1st link is about the cavity. It always uses at least 4 strips, two with small gap and between other two a larger gap. And also tells that different PCB materials behave different, everything is in boxed with a kind of absorber foam. \$\endgroup\$ Commented Dec 27, 2020 at 0:53

1 Answer 1


EM simulation is to pick cells per wave length. Typical filter centered at 10 GHz , then choose meshing at 20 Ghz and 50 cells per wavelegth


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