I want to design millimeter wave antennas

I want to design millimeter wave antennas for obtaining my PhD degree. my freqquency of interst above 60 GHz. Please tell me appropriate softwares at these frequencies. please Give some necessary advice..

I have used CST Microwave Studio. You can also use FEKO and HFSS but, personally, I don't have an idea about the latter two as I have not used them.

Get a copy of IEEE microwave magazine (any issue) and you will find advertising for 10 different EM simulation tools.
Get a copy of IEEE microwave magazine (vol. 9 number 6, Dec 2008) for a nice overview of different EM simulation techniques.

For your PhD work, start researching the different 60GHz antenna topologies (what type used where, and why).