Thanks for replies for all.
I also think HFSS is better solution for EBG, it takes more time.I have seen the paper by Zhang and Mansour (IMS2004) in which they have used the Momentum.
Momentum is much fatser than HFSS, but HFSS gives more acuurate results.
How can we appl the periodic bounadry conditions in HFSS, I am trying to define for 1-D periodic microstrip EBG, it gives the error.
Can we define the periodic boundary on the face we are launching the power.(i.e. plane wave)
-regards
popsy