What type of an antenna do you want to design? What bandwidth is needed? Give more information and then it's possible we can give you some suggestion or useful reference.
I'm trying to design an antenna using the HFSS but I dont know where to start. I would like to design a directional antenna that works in 2.45GHz ISM band. The gain should be around 8dB and provides a radiation angle that is less than 180 degree. Any help or suggestion would be great. Thanks