Software for Simulating The Input coupler of Cavity

Hi Friends
I want to design the coupler between RF waveguide and cavity of a linear accelerator.

I heard about HFSS, HFWORKS, MAFIA, ...
Please help me to choose the best software by comparing them

thanks

I think HFSS is better

Mafia.It's programmed for linear accelerator design

Have you used both HFSS & MAFIA.
Can you compare HFSS vs MAFIA?

No,I have never used Mafia but have rich experience with hfSS series.However I have used MWS which based on Mafia technique core.In my opinion, MWS is easier to use than HFSS,but HFSS is very powerful for one who have strong theory background because it is very versatility.

I guess you should choose a simulator according to the type/shape of the input coupler. The feasiblity(whether a particular software is useful)/speed/accuracy etc. all depend on that.