AnsweredAssumed Answered

floating CPW coupler

Question asked by mantow on Nov 21, 2005
Latest reply on Nov 21, 2005 by ALEPEREZ
How should one setup a Momentum simulation of a floating CPW coupler (2 conductor strips), which does not have bottom ground plane?

I tried assigning 8 separate single ports as follows;

1 ------------------------- 2
3 ------------------------- 4

The momentum results are imported into a schematic with an S8P component; ports 5 to 8 are set to ground. Response of thru port S21 agrees fairly well with CPWCPL2 model. However, the response from the coupled port S31 did not agree with CPWCPL2 model; coupling factor with momentum was over 4dB higher at design frequency. Isolated port response was also out by even more.

Then tried defining ground reference ports like this: 5 associate with 1, 6 with 3, 7 with 2, and 8 with 4.
Momentum simulation error then occurs: "ERROR: Invalid combination of single ports and ground references found. Please modify geometry."

What is the correct way of modelling a floating CPW coupler structure?