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 hf$$ series.However I have used MWS which based on Mafia technique core.In my opinion, MWS is easier to use than HF$$,but HF$$ 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.