Problem with stripline coupler design

[amihomo]

Hi
I have designed a UHF 30dB edge coupled stripline coupler on RO4003 substrate, everything was fine when i used HFSS waveports exactly at the ends of the stripline, but when i tried to extend the ports using microstrip lines, the port matchings are good but the isolation and directivity degraded.

How can I fix this problem?

 

[amihomo]

I fixed it

 

[soumyabumba]

Hi amihomo,

I am facing similar problemin HFSS in simulating a line-coupled BPF in stripline with microstrip transitions at both ends. When only the stripline part is simulated it is fine but when the microstrips are added the response is becoming distorted. Can you help me please on how to properly define the boundary conditions, waveports etc. and how to fix this problem?

Also currently I am simulating the trace conductor in both stripline and microstrip as a 2D-sheet. I want to give a 17um thickness to the copper traces and simulate. But doing that no response is coming. can u help me with that also?