I designed a simple 90 degree branchline coupler in ADS, tuned it to my liking (my values were very close to theoretical). Now, I simulate the structure in Momentum and my curves are all off, I get 3 dB less since it got shifted by several GHz.
Any suggestion and ideas why might my results be so different (and which one to trust)?
Schematic and Momentum simulation result may be different. If return loss is 3 db less then it's quite possible but insertion loss should be reduced such an extend .