Power Combiner EM Simulation in ADS Momentum

Hi everyone,
Now I am designing a power combiner module in ADS Momentum, as shown in the attached figure:

After simulating, I get 3*3 s-parameter matrix.
If I want to get some specifications of this power combiner(PB), such as efficiency, the maximum available gain, coupling coefficient, I need transform s parameters to z parameters for calculation.
Therefore, I use 2-port matrix equations listed as follows:

Z11=Zc*(1+S11-S33-(S11*S33-S31*S13))/( 1-S11-S33-(S11*S33-S31*S13)
Z22=Zc*(1-S11+S33-(S11*S33-S31*S13))/( 1-S11-S33-(S11*S33-S31*S13)
Z22=Zc*(2*S13)/( 1-S11-S33-(S11*S33-S31*S13)

But I doubt its correctness in this multi-port case, because the specs of PB I get using above Z params do not match my expectation seriously.
So I change my design like this by deleting port2 for the symmetry of port1 and port2.

Now I can use stoz function in ADS to realize transformation between Z params and S params.
This time I get better results.
But I still want to know how to simulate ILm, Efficiency, Gmax, Q and so on in multi-port case!

Does anyone have ideas on this topic?

Many thx!