Hi Juyoung,
As Scott already mentioned, to see the resonances you have to simulate the
whole board with proper boundary conditions - it might be difficult if not
impossible task.
An alternative is to evaluate the localization of the launch - compute how
much energy launch loses into the inter-plane environment and compare it
with the energy transmitted through the structure. The energy lost should be
minor fraction of the energy transmitted. All energy lost may cause
multi-path signal propagation with possible un-wanted resonances. Demo-video
#2016_10 at http://www.simberian.com/ScreenCasts.php -> How Interconnects
Work illustrates the launch localization breakdown phenomenon.
The dips in the insertion loss due to multipath propagation do happen in
practice. Localization of all transitions up to the target frequency is the
best way to prevent it. Also, at higher frequencies, the strip line should
be treated very similar to coplanar waveguide - the equipotentiality of two
reference conductors (planes) must be enforced for predictable behavior -
that can be done with stitching vias at electrically short distance from the
trace. Also, such vias can form channels for the signal propagation in
addition to the trace connection - the localization helps to prevent this
effect too.
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
2629 Townsgate Rd., Suite #235, Westlake Village, CA 91361, USA
Office +1-702-876-2882; Fax +1-702-482-7903
Cell +1-206-409-2368; Virtual +1-408-627-7706
Skype: shlepnev
www.simberian.com
Simbeor - Accurate, Productive and Cost-Effective Electromagnetic Signal
Integrity Software
2010 and 2011 DesignVision Award Winner, 2015 Best In Design&Test Finalist
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Juyoung Lee (Redacted sender "juylee2000" for DMARC)
Sent: Wednesday, July 12, 2017 2:04 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] ground plane resonance of stripline
Hi,
I am trying to build about 8 inch long stripline test structure.If there are
no ground vias stitched along the stripline except at end points, I can
imagine there would be resonances between the ground planes theoretically.
If it happens, would it appear as resonance dips in the insertion loss
curve?
Or is it a myth that wouldn't happen in practice? When I tried simulations
with HFSS for 2 inch long stripline, I didn't see resonance in S21.
Regards,Juyoung Lee
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