AnsweredAssumed Answered

ASYMMETRIC STRIPLINE and MOM WARNING

Question asked by symotecads on Nov 19, 2007
Latest reply on Nov 21, 2007 by symotecads
Hi guys.  I just have a question regarding the warning that I'm getting from my momentum simulation.  Basically I am trying to simulate an asymmetric stripline with the following stack:

GND
    MSUB1 (Er,Thickness)      3.66,0.76mm
METAL      stripline
    MSUB2 (Er,Thickness)      3.54, 0.1mm
GND

For simplicity we can ignore the metal thickness.  Now whenever I make my simulation, a stripline with line width of 0.17mm results in 50 ohm (at 12GHz), as displayed in my smith chart.  However, I do get this warning everytime:

Mesh generation at 12.7GHz.
port 2 : mesher chose to use an analytical (approximating) formula
to estimate the wavelength it needs to determine the maximum cellsize.
Mesh generation finished
S-parameter simulation
WARNING :
Port Solver failed to compute propagation constant and characteristic
impedance. 50 Ohm default impedance will appear in Dataset.
WARNING :
The 2D port solver data is not available,
using default values (50 Ohm) for the transmission line parameters.
Solver selection: automated choice of direct solver

My question is, is my line width correct for a 50 ohm stripline (using the above substrate stack) given that I am getting this warning during my simulations?  What do these warnings mean?

Appreciate help from you guys.  

Outcomes