Agilent reentered the 3D EM market with EMDS. EMDS uses the finite element method like Ansoft HFSS uses and the now obsolete HP HFSS used to use. You can run your EMDS license either standalone, OR integrated into ADS.
Now Ansoft HFSS is sold to Ansys, so it may not be around for long. Agilent has come back on the attack by introducing EMDS inside ADS and can use the same material properties and port setup as Momentum. So it is very easy to switch between Momentum and EMDS to plot and compare the results together. Some of the Ansoft HFSS developers have left to join Agilent so we may see HFSS capabilities creeping into EMDS