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Momentum - Dielectric constant vs frecuency issues

Question asked by simozz on Nov 9, 2020
Latest reply on Nov 12, 2020 by volker_muehlhaus



I am making some simulations for a stripline filter in Ku band (17.2 GHz) using a DiClad 880 Substrate.


Dielectric constant variation should be as plotted below


from .


However I see that in layout simulation the dielectric constant variation is significantly greater.

For example, the following is a plot of the filter response from schematics:


while the next one is the layout simulation:



To center the pass-band at 17.2 I have to manually tune the dielectric constant from 2.2 (schematics SSub) to 1.81 (layout substrate).


Could someone explain such a huge variation vs the datasheet plot ?