desing an antenna loop in hfss

i need to desing an antenna loop in hfss at 0.9 GHz
(1) draw a airbox; how to desing it a pure sphere?
(2) draw loop; an complete circule or maybe a symetric side
(3) add lump port;---- what about the boundaries
(4) setup the solver and simulate;
(6) obtain the S11 and farfield;