How is coplanar stripline fed in HFSS

I am using HFSS for simulating patch antennas (without ground planes). A center strip with two adjacent ground strips together constitutes feeding end of the antenna structure. Practically this antenna will be fed by a coax, center pin of coax connected to center strip of the antenna and ground strips coming in contact with coax's outer conductor through SMA jack. I don't know how to feed coplanar(three strip) structure in HFSS. Please help me out. It's urgent.