passband ripple gone

hello, i'm trying to design a chebyshev SI-LPF in ADS. My problem is that when i use microstrip lines(MLIN) instead of ideal transmission lines, the pass-band ripple vanishes. Instead, the S21 curve gradually decreases until it reaches Fc....
Is this a normal behaviour?

the ideal transmission line is no loss

Added after 20 seconds:

the ideal transmission line is no loss

the passband ripple exists only when ideal transmission lines are used?

The Non-Ideal TL's have loss so it sounds like the loss is taking out the ripple.
Just send your circuit to Momentum, that will give you a better picture of what
will happen.

Cheers