how to simulate DGS or finite ground plane structures in IE3D

i am currently doing my project work related to Defected Ground Plane Structures in IE3D.I am facing an error while simulating the DGS antenna or any finite ground plane structure.My queries are :
1) what feeding mechanism is used for finite ground plane structures
2)how to we define the port for finite ground plane structures
I have tried the tutorials available in IE3D but im not able for simulating them.I have attached the structures for DGS and finite ground plane.If possible please send in a tutorial for the same.