ADS simulation

I prefer fundamental mode Gnd--Positive--Gnd

I've ever tried two ways of drawing the CPW structures on ADS Momentum. One is you directly draw the ground and the line by defining "strip" for the conductor layer. Then you define a port in "single" mode for the line and two ports for the ground planes as "ground reference" mode. The S-parameters are alright but the port impedance is a bit weird (all 50ohms with frequencies). The other way is personally believed to be better when you just want to simulate a CPW structure itself. Rather than defining the tracks (gnds and line), you define a "slot" layer the structure which is just the gap between the ground plane and the line. Then you define "differential" mode for the ports and associate the ports at the same side as one. The results seem to be more convincing. The port impedance is alright with frequencies. Have fun.