finnish gps patch antenna

hi, i'm new in designing antenna, i work on project to design a patch antenna for GPS, and using CST Microwave studio, i just want to know how to calculate the axial ratio. and want to know how to get radiation pattern for farfield or know the zeros and max. of radiation because after i run simulation for far field i didn't understand the graphs in 3D so if any one can tell me the steps to know the previous.