I have made the Printed UWB Antenna Operating Over Multiple Mobile Wireless Standards design from IEEE page in hfss. But after designing I have error/warnings which is

[warning] Warning - Boundary 'Rad1' and Boundary 'gnd_plane' overlap.

Also I don't able to get s11 plot according to IEEE plot. How to get same s11 parameter graph.?

Also How to measure vswr from s11 plot in hfss.

IEEE document and HFSS design is also attach. Please help me on this problems.