Microstrip circuit Simulation
In ADS, you'll need to either


Get rid of the Port objects and connect a signal source and termination to the two ends of the trace. In recent versions of ADS, there is one Term object type that is used for both the stimulus and termination in S-parameter simulations.


or


Make a higher level schematic with a signal source and termination, that connects to an instantiation of this subcircuit as a 2-port.


Then


Add a simulation object to the schematic. You probably want an S_Param simulation object.
Click the "Simulate" button.
Graph the S(2,1) output data to get the transmission coefficient.