Why S11 result so different when changing frequency settings

[matianfu]

s11 settings + ads

I am using CST MWS to simulate an 2.4G U-slot patch antenna. I set the frequency range from 1 to 4GHz and tuned the antenna dimension to have an optimized bandwidth & S11. Then I changed the frequency range to 1.5 to 3GHz, I found the simulated result is quite different from the previous result. All other settings are the same and I am using the transient solver.

I can NOT understand why this happens. Which one should be more similar with the final product. Any advices?

 

[ravi8331]

Re: Why S11 result so different when changing frequency sett

this is bcoz of your maximum frequency is chnaged.
CST create the mesh cells according to the mximum lambda value which u are used .
that why ur results may be changed.

 

[matianfu]

Thank you very much.

I tried to check the adaptive meshing option and found after several pass, they eventually became almost the same.

Is this the way you recommend to solve my problem? The only painful thing is adaptive messhing takes too much calculation time. Maybe it worths as long as the result is right.

Thanks again.

 

[shahid78]

Re: Why S11 result so different when changing frequency sett

hi

well as mentioned by ravi , your results will be different if you change the maximum frequency of your range. this happens due to differnt mesh resolution

so its better to use adaptive meshing to get converged results for your final design

i hope it helps

regards