Coplanar waveguide characteristic impedence with cst

Hello everybody,
I have a doubt on the calculation of the characteristic impedance of a coplanar waveguide simulated on cst.
So, I have a simple not grounded coplanar waveguide. I excite this waveguide with two ports, by following the indication of the help in cst.
when I simulate the structure, how I can extract the characteristic impedance of my coplanar waveguide? the only parameter that I can see in the simulation results is the so called "line impedance", but I think that this is the impedance calculated for the port used to excite the mode of my cpw, and I'm not sure that this coincides with the characteristic impedance of the cpw. I suppose this because, if I calculate the caracteristic impedance of my coplanar waveguide with an online tool, I get different values.
I looked for a similar question in the forum, but I did not get the answer that I wanted
Any suggestion?
Thank You

if its 50ohm coplanar, you can terminate one end with 50ohm resistor and the other end with term. then simulate and check S11 (smith chart) and make sure its 50ohm in the smith chart.

Thank You for the reply.
So, you mean that I have to use lumped elements? To terminate the port with 50 ohms, I have to connect the two grounds, and insert the resistance as lumped element?
Moreover, what do you mean for term?
There's no way to extract the cpw impedance starting from a simulation obtained by exciting the two ports?
Thank You

hi alberto,
sorry to confuse you. are you familiar with ADS? ADS is circuit + EM simulator. CST is EM simulator. in recent times they have added circuit simulation capabilities i heard but i have nvr tried it myself.
my advice is for ADS. i dont know if CST got term. term is termination just like network analyzer termination when measuring s-parameter. im also not sure if CST have 50ohm resistor. So you can either import the layout or s2p to ADS and simulate there to verify the impedance of the line.

Hi pragash,
following your advice, I used cst design: by means of this tool, i can see my structure as a 2-port block. Te s-parameters characterize this block. I have two questions about that:
1. In cst, when I simulate my structure, it calculates the s-parameters by considering the input impedance if the exciting waveguide port. So, the results are normalized on this reference impedance. After the simulation, I can normalize this results on a 50 ohm input impedance. I suppose that I have to use this normalization if I want to put my cpw block in a circuit simulator.
2. Once I have the s-parameters, I take my block and I use it in a circuit simulator (cst design, as I said), as you suggested.Them, I run the simulation by placing 2 50-ohm elements at the 2 ports. The simulation, of course, gives me the s-parameters that I already had. Now, how can I extract the characteristic impedance of my block?
Thank you