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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:

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

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
Port Solver failed to compute propagation constant and characteristic
impedance. 50 Ohm default impedance will appear in Dataset.
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.