As suggested by Mr. Mohan, you will have follow book (balanis "antenna theory and design" ) to set your understanding upto advance level.
One more thing, in HFSS, you can design any type of antenna, so which antenna are you referring that matters.
You can also refer balbatia on microstrip antenna design.
Can you tell me, what are the different parameters need to consider to design an antenna using HFSS.. Available from: https://www.researchgate.net/post/can_you_tell_me_what_are_the_different_parameters_need_to_consider_to_design_an_antenna_using_HFSS [accessed Jul 27, 2017].